Kelty Cosmic Down 40

The Kelty Cosmic Down 40 is the warmest-rated, lightest bag in Kelty's Cosmic Down line, with a manufacturer comfort rating of 9°C and a limit of 4°C (40°F) that positions it for summer and mild 3-season nights rather than shoulder-season cold. At 740 g, with just 259 g of 550-fill-power DriDown duck down, it's built around minimizing weight for warm-weather trips rather than maximizing warmth range. The semi-rectangular cut, full-length two-way zipper, draft collar and draft tube, and DWR-treated recycled 20D nylon shell carry over the same construction details as Kelty's colder Cosmic Down bags, so the drop in weight comes almost entirely from reduced fill rather than a change in features. An internal pocket and included stuff sack round out the package. As a manufacturer-rated bag rather than one independently lab-tested, its stated temperatures should be treated as optimistic guidance, and hikers who sleep cold may want a comfort margin below the 4°C limit.