When it comes to innovation in outdoor gear, fabrics reign supreme. In recent years, backpacking brands have improved fleece hoodies and jackets by using lighter, more breathable fabrics, and now they’re bringing those same ideas to another important piece of gear: sleeping bag liners. A new crop of liners made with Alpha Direct fleece promises more warmth in a package that is drastically lighter than traditional models.
What is a Sleeping Bag Liner?
Liners — thin sleeping bag-shaped sacks of merino or synthetic fabric — help add insulation to your sleep setup. When used inside a sleeping bag, they can add 5 to 15 degrees of extra warmth, ideal for cold weather camping. They also help keep your sleeping bag clean. Backpacking is a dirty endeavor, and with liners, your dirt, sweat, oils, and more get on the liner instead of your bag. It’s much easier to toss a liner in the washing machine after a trip than it is to give your sleeping bag a thorough cleaning.
New vs. Old Models
Most brands make liners with either a synthetic polyester fleece or merino wool. Popular brands like Sea to Summit and NEMO use fabrics like grid fleece or proprietary recycled polyester blends. While these liners deliver on warmth, they’re also quite heavy. Sea to Summit’s lightest fleece liner weighs 9 ounces, and its warmest liner clocks in at 14.1 ounces, and NEMO’s flagship model weighs 12.5 ounces.
For many weight-conscious backpackers, that’s a lot of extra weight to carry for something they don’t strictly need, but that’s where Alpha Direct fleece comes in. This fabric consists of “a lofted fiber structure with a mesh core,” according to its manufacturer, Polartec. Essentially, a bunch of fluffy synthetic fibers are attached to loose, open knit. This open structure means it’s extremely breathable and fast-drying, and also very lightweight. It first got on backpackers’ radar when brands like Sambob and LEVE Outdoor Co. started making fleece hoodies with the material.
When it comes to sleeping bag liners, Alpha Direct versions are substantially lighter than traditional models, and typically add around 5 degrees of extra warmth. Liners from brands like Tumble On Outfitters and Allmansright only weigh 7 ounces. This cuts several ounces compared to Sea to Summit’s synthetic liners, and over 10 ounces compared to merino wool liners from brands like Cocoon.
One con with the fabric, however, is that it can be quite delicate. It’s easy to snag an Alpha Direct fleece jacket on a tree or rock, for example. These liners are not the kind that you should let your dog have access to, or use as a makeshift blanket around camp. If you keep it safe inside your sleeping bag, it should last. Be sure to store it in the provided stuff sack in your pack on trail.
Brands to Know
Manufacturers of Alpha Direct sleeping bag liners range from big-name outfitters to small cottage shops. Big Agnes makes a liner that weighs 7 ounces and retails for $150. New Mexico-based brand Tumble On Outfitters sells short and long versions of its liners, which weigh 6 and 7 ounces, respectively. Both models retail for $95, making it one of the most affordable of its kind on the market. Instead of the mummy shape that many liners use, this model has a rectangular shape to allow for more range of motion and a roomier foot box.
Swedish outfitter Allmansright’s Liners have several thoughtful details. The liners have loops on the front and end, so it’s easy to hang and air it out without it touching the ground. It’s designed for the neckline to gather into soft loops to frame your face and add extra warmth. The regular size weighs 7.5 ounces and retails for $120.
If you’re a weight-conscious backpacker, or just someone who always finds themselves shivering at night, these liners could become a helpful tool in your sleep setup.
