From trekking across the Swiss Alps to backpacking across Maine's highlands, the Big Agnes Hitchens UL 20 Degree Sleeping Bag retains fiery warmth without holding you back with unnecessary weight. This ultralight sleeping bag is rated to 20F for optimal warmth when overnights dip below freezing. The bag's nylon ripstop shell is both lightweight and extremely durable. It features a DWR coating that repels morning condensation from seeping through and compromising the down insulation inside. 850-fill DownTek insulation provides an exceptional warmth-to-weight ratio, satisfying the needs of lightweight backcountry enthusiasts. This down insulation features a hydrophobic treatment that repels moisture in wet environments. Ultimately, this means you'll stay pleasantly warm when drizzly conditions and high humidity levels threaten to leave you shivering-cold. Contoured baffles retain uniform heat distribution throughout the night. For greater warmth in windy conditions, the oversized draft collar locks in precious body heat from escaping.