Bison GWS

$1,185.00 - $1,225.00


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

Like all of Western Mountaineering's bags, the Bison GWS down sleeping bag is made by hand in San Jose, California. Their down is sourced from free-range mother geese who are never live-plucked or force-fed.


Brand Name:
Western Mountaineering
Bag Style:
Seasonal Usage:
Four Season
Temp Rating:
-40ยบ F
Temp Rating Celsius:
-40° C
850+ Fill Down
Bag Shell Material:
GORE® Windstopper™ 830 Fabric (GWS): windproof, virtually waterproof, and breathable
Bag Loft:
10 inches
Reg: 4 lbs 10 oz / Long: 4 lbs 13 oz
Fill Weight:
Reg: 42 oz / Long: 45 oz
Bag Length:
Reg: 6 ft / Long: 6 ft 6 in
Circumference at Chest:
Reg / Long: 64 in
Circumference at Hips:
Reg / Long: 55 in
Circumference at Foot:
Reg / Long: 39 in
Bag Stuff Size:
11 x 22 in
Made In:
Other Features:
  • Full GWS down-filled Super Collar completely surrounds your neck for maximum heat retention
  • Two interlocking GWS oversized down draft tubes mean zero cold spots along the zipper
  • Footbox made of abrasion-resistant taffeta, a more durable fabric woven with heavier yarns so the inside of your bag is protected when you store gear or boot liners at the foot of your bag
  • Stiffening tape along zipper to prevent snags
  • V-Block Side Baffles keep the loft where it belongs
  • Insulated External Hood Ruff

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