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 Gore Infinium sleeping bag is most often chosen to serve. A full Gore Infinium 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 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 Infinium collar seal in heat while howling winds surround your tent. The huge hood is not only well-filled but is completely made with Gore Infinium 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.