Western Mountaineering Bristlecone MF

The Western Mountaineering Bristlecone MF departs from the mummy shape used across most of the winter lineup: it's semi-rectangular with a differential cut, trading some thermal efficiency for noticeably more room to move and sleep on your side. Filled with 1191 g of 850+ fill power goose down for a total weight of 1787 g, it carries a manufacturer-rated limit of -23°C. Box-baffle construction keeps the insulation at full loft across the panel, wrapped in a water-resistant 20D MicroLite XP shell. A full-length, dual-slider zipper lets the bag open flat like a quilt or zip to a second matching bag to form a double — useful for couples on winter trips. An insulated draft collar and draft tube cut further heat loss at the points where mummy bags typically leak the most. Packed to 51 × 25 cm, it's a normal size for a winter bag but nowhere near ultralight — this reads as gear for hut-based or car-supported winter trips rather than lightweight backpacking. Made in the USA, sized for users up to 182 cm.