Marmot Lithium 0° Sleeping Bag

The Marmot Lithium 0° is a winter mummy bag rated to an EN/ISO comfort of -11°C, a limit of -14°C and an extreme of -35°C - firmly four-season territory for cold backpacking and alpine base camps rather than casual camping. Fill is 850-fill-power hydrophobic goose down, RDS-certified, with 793 g packed into a box-baffle build that resists cold spots better than simple stitch-through designs. At 1387 g in Regular size (fits up to 182 cm) it's reasonably light for its range, with a fill efficiency of about 1.77 g of down per gram of warmth. The Pertex Quantum ripstop shell adds wind resistance without much weight, while a fitted hood, draft collar and draft tube along the left-side zipper cut heat loss at the seams. An internal pocket, stuff sack and storage sack round out the package, and unlike most Marmot bags this one is cut unisex. Packed to 41 x 19 cm, compact enough for a standard pack, this remains a dedicated cold-weather bag - overkill above freezing and a poor pick for a versatile three-season sack.