Sea to Summit Ascent Down Sleeping Bag 0

The Sea to Summit Ascent Down Sleeping Bag 0 is a four-season down bag from the Ascent line, built for cold winter conditions with an EN ISO 23537 tested comfort rating of -11°C and a limit of -18°C. Insulation is 750 g of 750-fill-power duck down at a 90/10 ratio, hydrophobic-treated and RDS-certified. A box-baffle construction with vertical orientation keeps the down evenly distributed and limits shifting into cold spots, a common weak point on cheaper sewn-through bags. Shell and liner both use the same 20D recycled nylon with a DWR finish; total weight of 1,325 g works out to roughly 73.6 g per degree, a solid figure for the winter category. A triple-zip Free-Flow system (left-side zipper) allows ventilation control and lets two compatible bags couple into a double sleeping setup. A contoured hood plus draft collar and tube limit heat loss at the usual points. Suited to winter trekking and cold multi-day trips that need reliable insulation without the extreme weight of expedition-grade bags.