The CWM EQ -40degF Sleeping Bag by Marmot is stuffed to the gills with 800 Fill goose down for the ultimate in warmth when out in the coldest winter weather. The CWM EQ is a down bag that is surrounded by a waterproof/breathable fabric called MemBrain, keeping your bag dry and warm no matter what weather you encounter. Trusted on many mountaineering expeditions due to its durability, incredible weight to warmth ratio and all of the details Marmot added to make your sleeping experience just a little more peaceful. For example they added a 9 baffle chest section that runs vertically in core for maximum down control. Rolling from side to side wont shift the down, eliminating cold spots throughout the night. A nautilus 6 baffle hood has 6 chambers of down around the head for better down control and fit, and 11 baffles in the foot box are vertical to keep down around your feet. Stay warm through the night with the CWM EQ, that is until you have to use the restroom, than you are on your own.