The Hydrogen 30deg Sleeping Bag by Marmot is a super light, down filled bag designed exclusively for light and fast climbs and hikes. Weighing in at a wispy one pound, the Hydrogen still supplies incredible warmth with its certified 850 fill goose down that has the best weight to warmth ratio in the market. Stretch tricot baffles are added to provide the ultimate in strength, durability and bag life. A smaller and shorter zipper minimizes weight and a velcro free face muff keeps the drawcord and zipper away from your face while sleeping. For even more comfort there is a classic trapezoidal foot box for extra foot room and an insulated draft tube that eliminates cold leaks through the zipper.