The Western Mountaineering Cypress GWS Expedition is the heaviest bag in the lineup and carries the most down of any of them — 1415 g of 850+ fill power goose down for a total weight of 2210 g. Its manufacturer-rated limit of -34°C puts it alongside the Bison GWS Expedition among the warmest expedition bags on offer.
Box-baffle construction with a differential cut keeps the down evenly distributed under sustained loft, while the Gore Infinium (GORE WINDSTOPPER) shell adds a waterproof, windproof membrane that matters most on exposed high-altitude bivouacs. An insulated draft collar, draft tube, and fitted, adjustable hood cover the neck and head, and the dual-slider zipper makes venting or a quick exit easier.
Worth noting: the package doesn't include a compression stuff sack, only a storage sack for long-term keeping, so budget for a separate compression sack. This is clearly specialized gear for the harshest winter expeditions, not an all-purpose three-season bag. Made in the USA, sized for users up to 182 cm.
Specifications
Limit Temperature
-34 °C
Temperature Rating Standard
Manufacturer rated
Season Rating
5-season (expedition)
Total Weight
2210 g (4.87 lb)
Fill Weight
1415 g (3.12 lb)
Packed Size ( Length x Diameter )
56 x 28 (1.8 x 11.0 ft)
Insulation Type
Goose down
Fill Power
850
Fill Power Standard
US standard
Shape
Mummy
Baffle Construction
Box baffle
Baffle Orientation
Horizontal
Differential Cut
✓
Zipper Side
Right
Zipper Length
Full length
Two-Way Zipper
✓
Shell Fabric
Gore Infinium (GORE WINDSTOPPER)
Water Resistance
Waterproof/breathable membrane
Draft Collar
✓
Draft Tube
✓
Adjustable Hood
✓
Hood Type
Fitted/contoured
Storage Sack Included
✓
Size Category
Regular
Maximum User Height
182 cm (6.0 ft)
Gender-Specific Fit
Unisex
Country of Manufacture
USA
Warmth-to-Weight Ratio f(x)
15.4 °C/kg
Fill Efficiency f(x)
2.4 °C/100g
Weight per Degree f(x)
65 g/°C
Bag Type
Mummy sleeping bag
Where to buy
Failed to load offers.
Category context Sleeping Bags (417 products)
Weight
Expedition weight· mainstream zone 819–1420 g· ranked 400 of 418