Western Mountaineering Bison GWS Expedition

The Western Mountaineering Bison GWS Expedition is the warmest bag in the range, built for high-altitude and polar-range use, with a manufacturer-rated limit of -40°C. The fill backs that up: 1190 g of 850+ fill power goose down at a total weight of 2095 g, a ratio typical of dedicated cold-weather gear where warmth clearly outranks weight savings. V-baffle construction keeps the down from shifting into the corners of each chamber, holding an even insulation layer through repeated hard use — more important on an expedition bag than on lighter models. The Gore Infinium (GORE-TEX Windstopper) shell adds a windproof, water-resistant membrane, which matters most bivouacking in high wind or on exposed ridgelines. An insulated draft collar, draft tube, and fitted, adjustable hood cover the usual heat-loss points, and the bag ships with a one-year manufacturer warranty. This isn't three-season lightweight gear — at over 2 kg it's specialized equipment for the coldest expedition and high-mountain use. Made in the USA, sized for users up to 182 cm.