Mandatory Gear’s slogan is “ounces equal minutes,” meaning the lighter you are the faster you’ll be on the trail. The company, which focuses on gear for adventure racing and ultra-light backpacking, has some of the lightest-weight products on the market.

The company’s Bivy Sack, for example, weighs just 4.5 ounces and is made of waterproof silicon-impregnated nylon. It has no zipper, minimal breathability and nothing extra, but it does its job of keeping you dry in your sleeping bag in bad weather, and it weighs half that of many similar products.

Waterproof gear bags traditionally are made of a thick, heavy and cumbersome rubberized material. Mandatory Gear turns this design on its head, offering waterproof bags that weigh as little as 0.8 ounces and have 220-cubic-inches of capacity. They’re made of silicon-impregnated nylon and have waterproof zippers, not the roll-top design on regular waterproof bags.

For whitewater kayaking and other sports where the bag may become submerged underwater, Mandatory Gear’s bags are not ideal. You’ll want the security of a 100-percent watertight roll-top bag on the river. But for backpacking or other sports where your gear could get soaked from rain or even a quick drop in a stream, Mandatory Gear’s bags will do the job.

The company offers bags ranging from the 0.8-ounce small to its XL Zippered Dry Bag, a 4,500-cubic-inch bag that weighs a slight 2.5 ounces.

On a recent adventure race, my team used three of the XL Zippered Dry Bags to keep our backpacks dry on a canoeing section. The wide-mouth bags let us quickly throw a loaded backpack or two inside, zip it shut and go. The bags have large over-the-shoulder straps so you can carry them like duffel bags — a feature that was very convenient on the canoe portages.

All Mandatory Gear bags come seam-sealed and ready to use off the shelf. Other products of note from the company include rain paints that weigh only 2.6 ounces and a four-person, freestanding tent — called the Puppy Pile — that weighs a minuscule 1.56 pounds, including the carbon-fiber poles.

Contact: Mandatory Gear, 1-877-238-4327, http://www.mandatorygear.com

Pricing: Bivy Sack, $89. Waterproof bags: small, $18; medium, $22; large, $26; XL, $39.