Western's warmest bag at -40° F; windproof and highly water-resistant

　　Denali, Aconcagua, the Himalaya... mountaineering in the extreme. These are places where the margin for error is zero, and so the Western Mountaineering Bison GWS sleeping bag is most often chosen to serve. A full Gore® Windstopper™ shell makes this bag windproof and virtually waterproof while remaining lightweight and surprisingly compressible. Stuffed with over 40 ounces of 850+ fill down, the Bison GWS has 10 massive inches of heat-trapping loft. Huge V-Block Side Baffles and horizontal baffles across your chest keep the down fill in place, and double Interlocking Draft Tubes and a down-filled Gore® Windstopper™ collar seal in heat while howling winds surround your tent. The huge hood is not only well-filled but is completely made with Gore® Windstopper™ and has a large ruff to seal your face from the elements. The Bison is the crowning glory of Western Mountaineering and demonstrates their commitment to innovation and quality. This life-saving bundle weighs in under 5 lbs and is the warmest bag you'll find anywhere.

　　Like all of Western Mountaineering's bags, the Bison GWS down sleeping bag is made by hand in San Jose, California. Their down is sourced from free-range mother geese who are never live-plucked or force-fed.