Big Agnes Cinnabar -40°

The Big Agnes Cinnabar -40° is an expedition mummy sleeping bag built for extreme cold — its manufacturer-rated -40°C limit places it in the 5-season/expedition class, meant for high-altitude climbs and winter expeditions where a standard 4-season bag falls short. Fill is 850-fill-power down with DownTek hydrophobic treatment, arranged in vertical baffles that keep the insulation from shifting and thinning out. A Pertex Quantum Pro recycled ripstop shell and lightweight polyester taffeta liner keep total weight to 1,984 g for 1,361 g of down fill — a solid warmth-to-weight balance for this temperature class. An oversized draft collar and draft tube along the zipper cut heat loss, a full-length left-side zipper (single-direction, not two-way) opens easily for venting at camp, and an internal pocket holds small items close to the body. The bag is bluesign certified and PFC-free, relevant for anyone tracking the environmental footprint of their gear. The "short" cut (rated up to a 167 cm user height) suits smaller frames — taller hikers will need a longer version. A stuff sack and separate storage sack are both included.