Downright(r) Voyager 20 degreesF Rainier Down Rectangular Sleeping bag Bag Type: Mummy--Contoured design decreases the amount of space around your body, leaving less space to be warmed by body heat, creating a warmer, more efficient bag. Shell: Ripstop Nylon--A lightweight and durable fabric that has an added resistance to tears. Insulation: Premium 550+ Fill Power Natural Down--Captures and retains your body heat effectively. Construction: Slant Box Baffled Construction --Wall baffle prevents shifting of down insulation to help eliminate cold spots. Lining: Nylon Taffeta--A smooth fabric that is non-absorbing and dries quickly.