A Denali guides favorite. This is our bag of choice for the real cold. There are some very good bags made by other companies but none are made better than the Bison. If you will find yourself climbing Denali only once or will be out in the kind of weather this bag is made for it may be more bag than you need, but if you are looking for a bag to last for years to come there is none better.
The shell is of water resistant highly breathable DryLoft™. This bag is equipped with double oversized draft tubes to prevent heat escaping through the zipper. The hood has a reverse differential cut, the inner fabric is cut larger than the outer, to allow the down to flow around your face without having to cinch up the hood. A down collar fully surrounds the neck to prevent heat loss.

Western Mountaineering's Bison SDL