The NEMO Sonic -20 Sleeping Bag is a down sleeping bag for frigid nights outdoors. Stuffed with 800 fill power, hydrophobic down, this bag is as ultralight and packable as it can be, while still providing warmth on nights that drop to -20°F. It resists moisture better than untreated down, so you can still stay toasty warm when the snow, condensation and other damp possibilities threaten. Stretchy at the knees so side sleepers can enjoy comfort too, plus zipper-adjustable Thermo Gills for venting excess heat through the night, without letting drafts inside. Your winter backpacking nighttime companion you can't hit the trails without.