Featuring a three micro-layer knit structure, Expedition Weight SUPER MERINO WOOL maintains a layer of air between an exterior and an interior fabric. The layer closest to your skin pulls moisture away, spreads it out and moves it to the outer layer for faster evaporation. This action allows the layer of air to maintain a more constant temperature. Most people enjoy Expedition Weight base layers when involved in "stop & go" activities in cold weather. Ideal uses: cold weather mountaineering, ice climbing, skiing and snowboarding.