The Best Avalanche Beacons of 2024-2025

Avalanche beacons (also known as transceivers) are life-saving devices used by backcountry skiers and split boarders, mountaineers, hikers, or anyone venturing near or into avalanche terrain. We place a lot of emphasis on the type of skis, bindings, and boots you use for backcountry pursuits. However, rescue gear, like a beacon, is critical to survival, so why not choose the best avalanche beacon out there?

We extensively tested six avalanche beacons to determine which is the best on the market. We pitted each beacon against the rest in a variety of single and multiple burial scenarios. Lead tester Spencer Herford, an AIARE Course Leader who has been using and practicing with beacons for over 20 years, ran every beacon through multiple scenarios.

He also enlisted fellow professionals, former students, and several ski partners to help by using these beacons during testing. We did all our testing in the central Colorado mountains. We evaluated these beacons based on ergonomics, ease of use, ability to be updated, special features, and range. Whether you’re looking for a budget-friendly option like the Mammut Barryvox or a top-of-the-line performer like the Arva EVO BT, we’ve got you covered.

Below, you’ll see how the entrants fared based on our rigorous testing. To compare each beacon, check out our comparison chart. Peruse the buyer’s guide and FAQs to make an informed decision before buying the best beacon for your needs.

The Best Avalanche Beacons of 2024-2025

Best Overall Avalanche Beacon: Arva EVO BT
Best Budget Avalanche Beacon: Mammut Barryvox
Best Avalanche Beacon for Professionals: Black Diamond Guide BT
Most Innovative Beacon: Ortovox Diract Voice

Specs

Advertised Range: 60 m
Battery: AAA Alkaline or Lithium
Flagging Feature: Yes
Group Check: Yes
Auto Revert to Send: Yes
User Updatable Firmware: Yes

Pros

Good ergonomics
Long distance signal acquisition
Clear backlit screen
Group check mode tests transmit frequency and power
Excellent performance in single and multiple burial scenarios

Cons

Arva beacons tend to be harder to find in the U.S.
Beacon may feel small in hand if you have large hands

The Arva EVO BT ($389) stood out immediately in testing for its ability to acquire a signal reliably from very far away. It also rose above the rest due to the following features: its superb performance when looking for a single beacon or multiple, its clear backlit screen with easy-to-see directions during a rescue, and a very useful group check mode that checks for transmitting beacon signal frequency and power.

We will mention group check mode throughout our reviews. Group check mode is a valuable tool found on modern transceivers that allows you to easily make sure that all members of your group have their transceivers turned on and are in search mode.

During testing, the Arva stood out with its very long receiving range, which we found to be longer than advertised. Being able to cover ground quickly is helpful in an avalanche rescue, and with recommended search strips of 60 m, you can move fast. Some beacons have long ranges at the expense of picking up ambient electromagnetic interference (EMI), which confuses them. Still, the Arva does a great job managing that with its interference management software.

When used in scenarios, the Arva was always straightforward and intuitive in single and multiple burials. We could cover ground quickly to get closer, and the display arrows and distance were clear and easy to read. We found it worked well when guiding us through different phases of rescue. When multiple beacons are at play, the Arva can display up to four icons for four victims, and a plus sign for more than that.

A flagging option (flagging allows you to silence the signal from one device after you have located it to make it easier to locate the next closest signal) allows advanced users to ignore signals they have verified. Advanced techniques like the three-circle method or micro search strips (proven multiple burial techniques when the rescue situation is complex) worked wonderfully.

There is not too much to dislike about this beacon. Arva is a brand we don’t find as commonly in the United States as others in the test, so you might have a more challenging time finding it. But we think the Arva EVO BT beacon is great for any user. Whether you’re new to the backcountry scene or a professional, this is a solid all-around beacon. And, with the price of $389, you can’t go wrong here.

Specs

Advertised Range: 70 m
Battery: AAA Alkaline
Flagging Feature: Yes
Group Check: Yes
Auto Revert to Send: Yes – four minutes
User Updatable Firmware: No

Pros

Tenacious signal lock, no matter how sloppy the user is
Long range
Great ergonomics
Easy to read screen with best-of-the-best intuitive user interface

Cons

Multiple burial techniques like micro search strips are much harder to do with this beacon due to the tendency to lock onto signals and not let go
Long range comes at a cost of potential interference issues
Slower processing speed in the fine search

The Mammut Barryvox ($299) is a fully fledged avalanche beacon at a great price. For your money, nothing else on the market beats it.

The Mammut Barryvox has an advertised search range of 70 m. In our testing, this was accurate. However, the sensitivity of this and every beacon in our test when used a proper distance from sources of EMI (such as a phone, radio, satellite communication devices, and even something like car keys or heated gloves) is crucial. Because of the sensitivity, it’s easy to pick up phantom signals or even see incorrect distance and direction indicators. Every beacon we reviewed is susceptible to this. (Please read the FAQ for more details.)

A vital point for the Mammut Barryvox is the user interface. It has an easy-to-see screen, a confidence-inspiring mode slider with a lock, and icons and onscreen directions that are easy to understand. For example, if the arrows take you one way but your numbers are climbing, it will tell you to turn around with a U-turn icon. As you get closer, the screen shows when you should be bracketing in the fine search.

The Mammut is very tenacious on a signal when it’s locked on, something called signal drag. To the point where you can twirl the beacon around, and you won’t lose the signal or swap to another signal like many other beacons will. This is both a good thing and a bad thing.

The good: no matter how sloppy the rescuers’ technique is, they will probably have a successful time finding the beacon, as it’s hard to lose a signal once you have it. The bad: when you have multiple beacons in play, especially near each other, proven techniques like three-circle or micro search strips may not work as quickly as on other beacons due to this signal drag.

Also, when doing trailhead checks, the signal drag makes it very tough to make sure partners close to each other are all sending a signal. This is easily fixed by just using the group check mode, but anyone looking at this beacon should be aware of this beacon’s tendency to get locked on and stay on.

Fortunately, flagging works well on this beacon, making it easy and speedy when practicing multiple burial scenarios. With its long range and excellent user interface, the Mammut Barryvox is a great beacon for anyone looking to upgrade an older beacon or someone new to the backcountry world.

Specs

Advertised Range: 60 m
Battery: Alkaline or Lithium AAA
Flagging Feature: Yes
Group Check: Yes
Auto Revert to Send: Yes, disabled by default
User Updatable Firmware: Yes via app

Pros

Professional-grade beacon
Excellent performance in single and multiple burials

Cons

Slider to change modes has had a problematic history, and the redesign to fix previous issues is now harder to operate for some folks
Included harness tether is too short

The Black Diamond Guide BT ($500) avalanche beacon is a professional-level beacon with a wide range, excellent performance in single and multiple burial scenarios, and a comprehensive suite of unique features.

While it doesn’t quite have the extended range of the Arva or Mammut beacons we also tested, the Guide BT is fast and sure in processing signals. During the search phase, this beacon provides some haptic feedback with vibrations when it acquires a signal. This is a nice bonus to the straightforward, mostly easy-to-understand user interface. The screen is small and sometimes harder to read with polarized sunglasses.

The Guide BT has a group check mode, though it is a bit quirky in that you must continuously hold down the flag button. If you don’t, it reverts to send mode. This wouldn’t be an issue, except the button is a little tough to hold down, especially with gloves on.

The scan mode is an advanced function enabled while searching via the button next to the flag button that can be useful when you have multiple burials. When enabled, it shows the total number of victims within 5 m, then 20 m, then 60 m. Practiced users will be able to get a better sense of victims’ locations within the debris field and deploy resources accordingly.

Black Diamond has had a history with a predecessor of this beacon and the DSP Sport, with mode selection sliders not staying put and potentially turning the unit off when slid into the harness. This beacon, along with the Recon X, has redesigned and beefed up sliders that certainly seem to have fixed the issue. In making it stronger, it’s now a little more difficult to use, especially with thicker gloves on. In direct comparison to how other companies toggle modes, the slider design is certainly our least favorite design choice.

Beyond the ergonomics issues of the slider and small screen, we found this beacon to be incredibly powerful during testing. Recreationalists who would like to go with the Black Diamond beacons are better served by saving a few dollars and going with the Recon X, where you don’t give up too much. For professionals and advanced recreationalists who like great performance and can work with the design of the beacon, the Black Diamond Guide BT is an ideal choice.

Specs

Advertised Range: 50 m search strips
Battery: Rechargeable Lithium Ion
Flagging Feature: Yes
Group Check: Yes
Auto Revert to Send: Yes
User updatable firmware: Yes via app

Pros

Feels great in hand
Smart design choices
Large and easy to read screen
Voice assistance can keep rescuers on track, especially in the signal search phase

Cons

Noticeably shorter range
Rechargeable battery is not for everyone
Voice assistance could be more fleshed out

The Ortovox Diract Voice ($450) is a premium avalanche beacon that comes with a unique feature among avalanche beacons: it talks! Ortovox is a company known for very thoughtful design in all its products, and using this beacon you have to be impressed with how nice it feels in hand.

The standout feature of this beacon is voice guidance, which can be turned off in the companion app (there is also the Diract without voice assistance). Testers found the voice guidance to be useful, particularly if we were in a real rescue situation where we would be very stressed and not thinking as clearly.

For instance, if you are following a flux line and getting farther away, the Diract Voice will tell you to “Turn Around!” Simple, but effective in correcting a mistake — following a signal the long way around — that is often made by backcountry users who are learning about beacons or those who don’t practice enough.

From a distance, the voice guidance works well and is helpful for a less practiced individual. As you get closer to the beacon you are looking for, the guidance is more limited, and many testers found it almost distracting rather than helpful. There is so much potential here; well done, Ortovox, for the innovation!

Without voice guidance, this is still a great beacon with two potential caveats. First, it has a noticeably shorter range than any other beacon we tested. It’s still well within the minimum search strip width of 40 m that many avalanche courses will use, but when some other beacons have nearly double the range, it’s noticeable.

The other noticeable difference is the Diract Voice uses a rechargeable lithium-ion battery versus replaceable batteries. In testing, the Ortovox lasted similar lengths of time between charges as any other beacon with AAA batteries. If you forget to charge your battery, you run the risk of being out of battery and not going skiing or going with a battery without enough charge in it to safely do a rescue. Remember, your beacon will use significantly more power in search than in the send/transmit mode.

Using the beacon without voice guidance, it processes single and multiple burial scenarios very well. The design of the beacon is well thought out, making it easy to swap between modes with gloves on.

The Ortovox Diract Voice has a lot going for it. For newer backcountry users, voice guidance could work really well to help a rescuer in a very stressful situation. We’re very excited to see where voice guidance technology in beacons can go moving forward.

Specs

Advertised range: 60 m
Battery: Alkaline or lithium AAA
Flagging feature: Yes
Group check: Yes
Auto revert to send: Yes, enabled in app
User updatable firmware: Yes, via app

Pros

Excellent performance in single and multiple burials
Great value
Fast performance in fine search

Cons

Slider to change modes has had a problematic history, and the redesign to fix previous issues is now harder to operate for some folks
Screen is small/can be tough to see

The Black Diamond Recon X ($350) is a more streamlined version of the company’s professional-level Guide BT beacon. While you lose some advanced features, you still get the blazing-fast processor that performs awesomely in single and multiple burial scenarios. It also has some bonus features like group checks and the ability to use lithium or alkaline batteries.

This beacon, in practical use, doesn’t quite have the range of the Arva or Mammut beacons, but it sure is close enough not to be a huge deal. Once the Recon X has a signal, it will guide you with a simple user interface of arrows and distance. Like the Guide BT, the screen can sometimes be harder to see if you use polarized sunglasses, and it feels small. In testing, we did feel the Black Diamond beacons did really well in the fine search when rescuers were in the critical 5 m range. There is no metric to point to for it being any faster; it was just the impression that the processor was very fast and was harder to overrun like some other units.

For special features, you still have flagging and a group check mode. The Recon X flag button is larger than the Guide BT, and we had an easier time holding that button to use group check mode. We wish you did not have to hold it down the entire time during the group check, though.

Black Diamond has a history with the predecessor of this beacon, the DSP Sport. Its mode selection sliders did not stay put and could potentially turn the unit off when slid into the harness. Its redesigned and beefed-up slider certainly seems to have fixed the issue. However, by making it stronger, it’s now a little more difficult to use, especially when wearing thicker gloves.

Beyond the ergonomics issues of the slider and a smaller screen with some older feeling user interface icons, this beacon shone for his power and performance during testing. If you are looking for your first beacon or replacing an older beacon, the Black Diamond Recon X is a great choice if you can work with the ergonomics.

It’s a much easier beacon to find in the U.S. than our best pick (the Arva EVO BT), and it usually comes in a package with a shovel and probe. For professional or advanced recreationalists, you might like the Guide BT more.

Specs

Advertised Range: 50 m
Battery: AAA Alkaline
Flagging Feature: Signal suppression for 60 seconds
Group Check: No
Auto Revert to Send: Yes, must be activated every time when powering up
User Updatable Firmware: Yes, via PC connection (mac not supported)

Pros

Fast processing
Simple and proven user interface
Glove-friendly design

Cons

As useful as big picture mode is, multiple burial performance suffers due to signal suppression quirks
Letter designations and icons are not as intuitive as other beacons tested

The Backcountry Access Tracker 4 ($399) is BCA’s flagship avalanche beacon, featuring a sturdy case with glove-friendly buttons and a simple and reliable interface. BCA beacons are ubiquitous in avalanche courses and guide operations and are found in the gear closets of many recreational backcountry skiers and riders in the United States. They aren’t flashy, nor do they have the longest range or the coolest special features, but they do the job for which they were designed: avalanche rescue.

During testing, the Tracker 4 never really stood out in any way when directly compared to other beacons, but it also doesn’t have many glaring shortcomings either. In single burial scenarios, the Tracker 4 performed well, with a recommended search strip width of 50 m. Once it acquires a signal, the processor is fast and accurate, bringing you within range quickly.

The simple two-digit display does the job of giving you direction and distance. You must absolutely learn the details about what the different two-letter designations and multiple burial icons mean in the context of a rescue situation, as it’s not always obvious what is going on.

The Tracker 4 isn’t as great in multiple burial situations as other beacons we tested. Signal suppression works by being close to a transmitting beacon and hitting the suppression button, which temporarily masks the closest signal and gives you directions to the next closest signal. This is done to ensure that a rescuer is not masking the incorrect signal. In practice scenarios, signal suppression is functional but does feel confusing and not as intuitive as other beacons that use a flagging feature.

The Tracker 4 has another mode called big picture, which cycles through all beacons transmitting within range and their rough distance and direction. This can give a good picture of the situation and how to go about deploying rescue resources. However, it requires practice to fully grasp what the display is telling you about the situation.

The BCA Tracker 4 combines a rugged case with a simple user interface to make a beacon that is easy and reliable to use for most people.

Avalanche Beacon Comparison Chart

Avalanche Beacon	Advertised Range	Battery	Flagging Feature	Group Check	Auto Revert to Send	Updatable Firmware
Arva EVO BT	60 m	AAA Alkaline or Lithium	Yes	Yes	Yes	Yes
Mammut Barryvox	70 m	AAA Alkaline	Yes	Yes	Yes – four minutes	No
Black Diamond Guide BT	60 m	Alkaline or Lithium AA	Yes	Yes	Yes, disabled by default	Yes via app
Ortovox Diract Voice	50 m search strips	Rechargeable Lithium Ion	Yes	Yes	Yes	Yes via app
Black Diamond Recon X	60 m	Alkaline or lithium AAA	Yes	Yes	Yes, enabled in app	Yes, via app
BCA Tracker 4	50 m	AAA Alkaline	Signal suppression for 60 seconds	No	Yes, must be activated every time when powering up	Yes, via PC connection (mac not supported)

Avalanche pro and avid backcountry enthusiast Spencer Herford led the way in testing the best avalanche beacons; (photo/Elk Raven Photography)

How We Tested Avalanche Beacons

Why You Should Trust Us

Our main tester, Spencer Herford, is an avalanche instructor, backcountry skier, and split boarder who has been using beacons for over two decades. He is an AIARE Course Leader, split board and ski guide, and a graduate of the Colorado Mountain College Avalanche Science Program. Fortunate enough to learn from countless leaders in the avalanche safety realm about snow science and rescue, Herford has participated in, led, and designed countless rescue scenarios.

As an avalanche educator, he has had the honor of starting many people’s backcountry careers. Often, this includes coached rescue drills. As a result, he gets to see every beacon on the market used in a range of rescue scenarios. This makes him uniquely poised to advise how each beacon shines and where each could use some improvement. Because he is out there over 100+ days a year, year after year, Herford also stays abreast of technological advancements. He also has his finger on the pulse of improvements (or failures) made on beacons from year to year.

Our Avalanche Beacon Testing Process

We used each beacon in single and multiple burial rescue scenarios designed to mimic real situations a rescuer might face. Each beacon was tested multiple times in these mock rescues. We looked at how fast each processed signals and how well it handled EMI. We also tested to see how it operated with gloves on and how intuitive it was to use. We enlisted the help of backcountry partners, former students, and professional colleagues to give more targeted feedback on scenarios.

We tested in several venues in central Colorado, many of which are used in avalanche education courses. These are usually large open areas free from distraction that simulate a debris pile. Each scenario started from the point last seen, which was outside of the search area. We then turned the beacon to search mode and started search strips to find the signal, usually in 40 m strips.

As we tested beacons, we also tried the manufacturer’s recommended search strips to gauge how well those worked. Once a signal was acquired, we followed the arrows and distance to the sending beacon. As we approached below five m, we did our fine search with the beacon close to the snow surface. After finding the lowest number, we verified with a probe strike.

Beyond rescue simulations, we also carried these beacons on personal backcountry tour days. We did trailhead departure checks to make sure each member had adequate battery power (usually above 60%) and could send and receive a signal. We also looked for how well the supplied harness carried the beacon or how the beacon fit into a dedicated rescue pocket in ski pants. If you’re looking to round out the rest of your touring kit, check out our guides to the best backcountry skis, bindings, and boots and our latest round-up of the best climbing skins.

Buyer’s Guide: How to Choose the Best Avalanche Beacons

Avalanche rescue technology is an ever-changing landscape. Just look at how beacon technology has changed in recent memory. We started with single-antenna analog beacons that were difficult to use. We have now progressed to new modern three-antenna beacons that are incredibly intuitive and fast, even for new users. We would recommend you consider a few things when choosing an avalanche beacon.

Ergonomics

Everyone has different-sized hands and uses different types of gloves outside in winter. Some folks deal with freezing hands and use thicker gloves. We encourage you to wear the gloves you plan to use most often when trying out beacons. Make sure you can turn it on and switch modes effectively. Taking gloves off to use rescue gear can lead to cold or wet hands. We tried each beacon with various gloves to see how easy it was to use. The Ortovox Diract Voice stood out among the tested beacons as the most comfortable and easy to use.

Range

Range, or the distance from which a beacon can pick up a signal is a complicated metric. Although important, it’s not the only factor to rely on when choosing a beacon. It makes sense to want to pick up a signal from as far away as possible because this allows rescuers to get to the actual grunt work of the rescue (shoveling) more quickly.

However, in some cases, the ability to pick up a signal at a more extended range comes from a beacon’s increased sensitivity. Ultra-sensitive beacons can be prone to more cases of EMI, which can make a rescue more difficult due to phantom signals or misdirection. Mitigating EMI is an area of notable innovation in the past few years. Many beacons are integrating software to handle this interference. In some cases, beacons can even mask it or process it out. Some beacons we tested will also notify you of EMI with an icon. Or, they will tell you to shorten search strips to better filter out the noise.

Generally, our testers recommend beacons with more extensive receiving ranges because rescuers can close the gap to a victim faster. It also increases the potential to pick up multiple buried victims faster to deploy resources better. The Arva Evo BT and Mammut Barryvox are the clear winners for range in the test. The Black Diamond BT Pro and Recon X rank close behind.

The **Black Diamond Guide BT** boasts several features that make it ideal for professionals (photo/Elk Raven Photography)

Special Features

At the basic level, an avalanche beacon needs to be able to send and receive a signal from other beacons. Beyond that, we see a few special features that can be helpful depending on how you plan to use the beacon.

Flagging

A major one is a flagging mode, which essentially tells your beacon to ignore a signal and give information on the next signal. This is helpful in multiple burials; many professionals see this as essential. For recreationists, if you are skiing in avalanche terrain, the best rule you can follow is to expose only one person at a time to the hazard. Many times, recreational avalanche rescues tend to involve only one buried individual, which makes flagging less critical. If you use flagging, you need to be absolutely sure you are masking the correct signal.

Group Check Mode

Beyond flagging, many beacons can feature a group check mode, which is helpful for making sure your partners are sending a signal. This mode shortens the beacon’s receiving range and allows for these departure checks even if there are many other groups around you.

Auto Revert to Send

Imagine if you were conducting a rescue and another avalanche came down on some of the rescuers. If they were all in search mode, rescuers not caught wouldn’t be able to find them if their beacons stayed in search mode. On some models, the “auto revert to send feature” kicks in when a beacon doesn’t sense movement for 2 to 4 minutes, and it automatically reverts to send.

Big Picture/Overview

The Black Diamond Guide BT and the BCA Tracker 4 both feature a special mode that gives an overview of the rescue field by showing where multiple signals may be located. The Black Diamond mode shows the number of beacons at different distances away, and the BCA mode cycles through all the signals with a direction and distance. For practiced users, this is a great tool for gauging how to deploy resources accordingly.

The **BCA Tracker 4** is a tried and true product that has stood the test of time; (photo/Elk Raven Photography)

Updateable

We are all used to updates in the digital world, and our beacons are no different. New and improved features, better processing algorithms, battery optimization: all of these things can be improved in software updates. Many beacons are moving to make these updates very easy to manage through companion apps so your beacon is the best it can be. The Arva, Black Diamond, and Ortovox all come with app support. The BCA Tracker 4 can be updated via USB, but only on a PC. The Mammut Barryvox requires a trip to a dealer.

The **BD Recon X** has a large receiving range and can easily be updated via an app making sure it stays current and performs well; (photo/Elk Raven Photography)

Ease of Use

How intuitive is the beacon for you to use? Is it obvious how to turn it on and off? Do the icons on the screen make sense? In rescue situations where your partner could be buried below the snow, you are their lifeline! This is a huge responsibility. Having a beacon that is easy to switch into search mode, with a screen you can see and directional prompts (visual or audio) you can easily follow, is crucial in a situation where every second counts.

Being calm and level-headed in a rescue situation is critical for your partner’s survival. Using a beacon that provides clear direction could help with that. We really appreciate the on screen prompts of the Arva EVO BT, the Mammut Barryvox, and the Ortovox Diract Voice.

Our best overall pick, the **Arva EVO BT** is intuitive and has great on-screen prompts; (photo/Elk Raven Photography)

Freaquently Asked Questions

Avalanche beacons save lives. Many avalanche fatalities in the United States still occur because the victim was not wearing an avalanche beacon. This makes their partners attempt to find them equivalent to “finding a needle in a haystack.” Its tragic that these deaths still occur when life saving technology is widely available. A successful rescue is not just dependent on the correct equipment. It’s also critical to be well practiced in rescue with your touring partners so you are ready to respond instantly.

Absolutely! All brands of avalanche beacons use the same frequency: 457kHz. This is an international standard. Rest assured, you and your partners will all be sending and receiving on the same frequency. That said, older beacons have a tendency to “drift” from this 457kHz signal standard.

It’s recommended to test for this drifting every year after your beacon hits the five-year mark or so. A beacon that no longer transmits on the correct frequency cannot be found by other beacons. Many manufacturers offer a summer service to check your beacon is functioning properly. Some beacons, like the Arva Evo BT, even have a group check mode that can check other beacons in your group for frequency drift.

A smartphone is an essential item when ski touring. Digital mapping, camera, trip planning, emergency communications, etc., are all critical for a day out. Even a cellphone in airplane mode can interfere with a beacon. It is recommended to keep a phone (and any electronic device) at least 8 inches or 20 cm away from a transmitting beacon. In search mode, the distance should be at least 20 inches or 50 cm away, and at least 36 inches or 1 m away if you are sending a signal with the phone, like calling for help.

Avalanche beacons send and receive a radio signal at 457 kHz. A beacon can be susceptible to interference from other electronic devices and metal objects if they are too close to your beacon. In general, experts recommend a minimum of 8 inches (20cm) of distance from a beacon in the send/transmit mode, and at least 20 inches (50cm) from a searching beacon. Interference is more likely when searching, and especially at your beacons maximum reception range.

This Electromagnetic Interference (EMI) can look like incorrect distance or direction reading, signals that pop up and go away, multiple signals when there shouldn’t be, etc. Many beacon manufacturers are starting to integrate software that senses EMI and will tell the rescuer to remove the source of interference if possible, or shorten search strips.

Black Diamond did extensive work on testing common electronics and how they can interfere with beacons in search mode. Common culprits of EMI include smart phones, radios, smart watches, satellite communication devices, snowmobiles, heated gloves, and even ambient conditions like nearby high voltage power lines can all interfere with your beacon in various degrees of severity. We would strongly encourage careful consideration and testing of the personal devices you choose to carry into the backcountry, and how they might potentially interfere with a beacon search.