The NEMO Equipment Inc. Sonic -20 Degree Down Sleeping Bag provides us with cozy relief from brutal winter chill. This toasty bag can handle frigid temps while we're putting in high camp on an unsupported expedition, but the ventilation allows for comfortable use in warmer weather as well. The 800-fill down is lightweight and compressible, making it easy to stuff in your pack for a multi-day traverse, and the DWR-treated nylon ripstop material fights off moisture and withstands wear and tear from life on the trail. The draft collar seals in heat and keeps chilly air out, while Thermo Gills allow efficient ventilation in the warmer months.