Mountain Hardwear Phantom™ 0F/-18C

The Mountain Hardwear Phantom 0F/-18C is a 4-season winter mummy bag with 850-fill, 90/10 goose-down/feather ratio, RDS-certified fill (805 g fill weight) inside a 10D recycled nylon Ghost Ripstop shell with a 20D nylon taffeta liner. Down is distributed through horizontal box baffles, a construction that resists cold spots better than sewn-through designs, though it adds a little weight versus the simplest ultralight builds. EN/ISO 23537 testing rates it at -11°C comfort and -18°C limit, down to -39°C extreme — genuine winter numbers rather than a stretched 3-season bag. Total weight is 1172 g, giving a warmth-to-weight ratio that reflects a real winter fill load rather than a lightweight compromise; packed size is 42 x 21 cm, noticeably bulkier than the brand's 3-season Phantom bags. The 3D anatomical hood, draft collar, and draft tube target the usual winter heat-loss points, and the bag is coupleable for pairing with a matching size. This is a dedicated cold-weather bag for winter backpacking, alpine base camps, or shoulder-season trips into serious cold — not a bag to carry when a 3-season rating would do, given its added weight and bulk.