A light weight next-to-skin base layer is the base of any layering system. Breathability and moisture wicking are essential for high output cold weather activities like ski touring. The Light Crew base layer from The North Face is made from anti-odor polyester fabric with FlashDry Eco technology. This both increases the sweat wicking and dry time from said sweat. The fabric is sticked together with flat-lock seems for comfort in the next-to-skin fit. Get out there and give'r without getting swamped out and cold at the summit.