Built for mountaineering on the world's tallest peaks, the Western Mountaineering Bison STS -40 sleeping bag keeps you warm in the coldest places with 42 oz. of 850+ fill-power down insulation.
Fill
850+ fill-power goose down
Weight
6 FT Left Zip: 4 lbs. 5 oz.
6 FT 6 IN Left Zip: 4 lbs. 10 oz.
Compressed Volume
6 FT Left Zip: 24.6 liters
6 FT 6 IN Left Zip: 25.7 liters
Temperature Rating (F)
-40 degrees (F)
- Weather-resistant Storm Shield shell protects against extreme wind and moisture, while maximizing inner breathability
- 42 oz. of 850+ fill-power ethically-sourced premium goose down creates 10 in. of heat-trapping loft for a rating of -40°F
- Storm Shield-lined insulated external hood ruff seals the bag from freezing temperatures while retaining internal heat
- V-Block side baffles provide phenomenal down control and improve insulation in colder temperatures
- 2 interlocking draft tubes seal the sleeping bag against cold wind and help retain inner temperature
- Offset insulated double draft tubes
- Durable, abrasion-resistant footbox lining is great for storing heavy boots and alpine equipment
- Comes with an ultralight stuff sack and a breathable mesh storage bag
- Weighs in at 4 lbs. 10 oz.
- EN Testing not available at these colder temperatures
Made in USA.
View all Western Mountaineering Backpacking Sleeping Bags| Best Use | Backpacking |
|---|---|
| Temperature Rating (F) | -40 degrees (F) |
| Temperature Rating (C) | -40 degrees (C) |
| Weight | 6 FT Left Zip: 4 lbs. 5 oz. 6 FT 6 IN Left Zip: 4 lbs. 10 oz. |
| Shell | Storm Shield |
| Zipper Location | Left |
| Insulation Type | Down |
| Fill | 850+ fill-power goose down |
| Fill Weight | 6 FT Left Zip: 2 lbs. 10 oz. 6 FT 6 IN Left Zip: 2 lbs. 13 oz. |
| Sleeping Capacity | 1-person |
| Lining | Nylon taffeta |
| Sleeping Bag Shape | Mummy |
| Fits Up To (in.) | 6 FT Left Zip: 72 inches 6 FT 6 IN Left Zip: 78 inches |
| Shoulder Girth (in.) | 6 FT Left Zip: 64 inches 6 FT 6 IN Left Zip: 64 inches |
| Hip Girth (in.) | 6 FT Left Zip: 55 inches 6 FT 6 IN Left Zip: 55 inches |
| Stuff Sack Size | 11 x 22 inches |
| Stuff Sack Volume | 34.26 liters |
| Compressed Volume | 6 FT Left Zip: 24.6 liters 6 FT 6 IN Left Zip: 25.7 liters |
| Gender | Unisex |