The 9 cm thick Dura 8R utilizes Exped's Downmat technology: the air compartments contain down that prevents air from circulating between the areas heated by your body and the air cooled by the outside air. The R value describing the insulation is 7.8 and the lowest operating temperature recommended by the manufacturer is -40C. The Dura series has more durable surface fabrics than other R pads: 75 denier per sleeper and 170 denier ripstop fabric at the bottom - the difference to ultralight 20 ... 40 denier fabrics is very noticeable. - MW size: 183 cm long, 65 cm wide - Insulated with down A Schnozzel pump bag is included to fill the base without the need for blowing. Blowing draws moisture into the substrate and the use of a pump bag reduces fainting.