To some people winter mountaineering is just a pastime. Be it searching for an uncut bowl to tele, a frozen waterfall to climb or a simple visit to the Brooks Range, the Western Mountaineering Puma Gore Windstopper has been there, done that! This sizable bag is lofted with down and roomy to boot! 37 ounces of 850 fill power down lofts this bag to a full 9 for a rating of minus 25 below! A shoulder girth of 64 provides room to layer, store clothing or fit to big folk. The inside foot section is sewn with a 2.4 oz. fabric to protect the bag while stowing gear. And the Reverse Differential Hood is roomy, down filled and warm, and totally made with Gore Windstopper. The full down filled collar and both Interlocking Draft Tubes are also completely made with Gore Windstopper fabric. No place to cut costs! Few continents require anything warmer than the Puma Gore Windstopper!