Sea to Summit Ascent Down Sleeping Bag 25

The Sea to Summit Ascent Down Sleeping Bag 25 is the lightest bag in the Ascent lineup, at just 860 g. A comfort rating of 2°C and a limit of -4°C (EN 13537) place it among three-season bags for milder weather — spring, summer, and early autumn at lower to mid mountain elevations. The 330 g duck down fill (750 fill power) sits in H-baffle chambers with mixed orientation, hydrophobic-treated and RDS-certified. The smaller fill reflects the milder temperature target — a figure of roughly 215 g per degree is high within the category, typical for light warm-weather bags, since even a small amount of extra insulation costs proportionally more weight at this end of the range. A two-way zipper with draft tube and an internal pocket round out standard features, and the coupleable design suits pairs sharing a camp. Shell and liner in the same 20D recycled nylon keep total weight low. A solid choice for those who want the lightest bag for the warmer part of the season without margin for freezing nights.