Marmot Men's CWM -40° Sleeping Bag

The Marmot CWM -40° is a full expedition-grade mummy bag, manufacturer-rated to a -40°C limit for genuinely extreme cold - polar travel, winter mountaineering, or anywhere survival-level insulation matters more than pack weight. At 2266 g it's one of the heavier bags in Marmot's range, but that's largely the cost of the rating: warmth-to-weight sits around 56.7 g per degree of protection, efficient for a bag this warm. Unlike most down bags, the 800 fill-power goose down here isn't treated hydrophobic; moisture protection instead comes from the shell - a two-layer Pertex Shield waterproof-breathable membrane over a Pertex Microlight liner, keeping down dry from condensation in a way DWR alone cannot. A center, two-way full-length zipper vents from either end, a 3D anatomical hood seals tightly around the face, and a draft collar plus draft tube minimize heat loss. RDS-certified down, a stuff sack and storage sack are included, cut men-specific up to 182 cm. Packed size is 56 x 31 cm, reflecting the loft needed for -40°C performance - specialized gear for a specific trip.