Stay warm and comfy in the Therm a Rest Altair HD 10 Degree Down Sleeping Bag while you listen to the soothing sound of snow blanketing your four season tent. Designed to keep you comfortable at 23 degrees Fahrenheit and handle temperatures down to 10 degrees Fahrenheit according to European comfort ratings, the Altair is just the bag to pull from your pack after a full day of ski touring or mountaineering. It's zoned insulation places 85% of the insulation at the top of the bag where heat tends to escape, while the Synergylink connectors attach the bag to your mattress where it will do most of the insulating between you and the ground. Hydrophobic down fibers will retain their loft if they happen to get wet, and the ThermaCapture lining reflects warmth without adding excess weight. A draft tube and collar prevent heat loss along the zipper and top of the bag. Cinch the hood down when the temps drop throughout the night, and sleep comfortably on your side, back, or belly thanks to the differential cut.