Multi day mountaineering and alpine ascents require a hard working bag like the Mountain Equipment Matrix I sleeping bag. This bag features a combination of water resistant down and Primaloft synthetic insulation to ensure the warmest night's sleep possible, even in wet, damp conditions. An alpine fit ensures you're not hauling around extra material, nor are you wasting energy heating up excess space in the bag at night. A baffled hood and Solus draft collar help with heat retention and prevent cold air from seeping in. The 34 length side zip is convenient without adding too much weight, and the included stuff sack makes for convenient storage and travel.