Western Mountaineering Puma GWS Expedition

The Western Mountaineering Puma GWS Expedition is a five-season mummy bag rated to a -32°C limit, built for polar and high-altitude expedition use rather than ordinary winter camping. It carries 964 g of 850 fill-power goose down in vertical (V) baffles with a differential cut, wrapped in a Gore Infinium (Windstopper) shell — a windproof, breathable membrane that adds protection against wind-driven heat loss and light moisture that a plain nylon shell cannot match. At 1617 g, it is among the heaviest bags in Western Mountaineering's range, but a weight-per-degree figure near 50 g reflects how much warmth that weight buys at extreme temperatures — the Windstopper membrane adds mass the fill power alone can't offset. Draft collar, draft tube, and an adjustable, fitted hood seal the remaining heat leaks; the short-length cut (up to 167 cm) is the standard trim for Western Mountaineering's expedition-grade bags. This is specialist gear for high-altitude mountaineering, polar travel, or genuine winter expeditions where wind resistance matters as much as raw insulation — far beyond what typical backpacking or thru-hiking requires.