The Gemini Series is a premier line of ultralight weight down sleeping bags that incorporates the features that we have found to be essential in our more than 30 years of cold weather experience. The outer fabric is a 1.0 oz/yd² 20 denier mini-ripstop nylon and the inner fabric is a 1.0 oz/yd² 20 denier nylon taffeta that is very soft to the touch. 800 fill power, water-resistant goose down is used throughout the series. The Gemini Series is available in three temperature ranges, 20°F (-7°C), 0°F (-18°C) and -20°F (-29°C), all with the same features and interior dimensions. The bags vary in thickness depending on the temperature range and the amount of down used.