This base layer crew is an ideal layering piece for all-day warmth and comfort while being out in the elements. This versatile piece features an ultra-soft, mid-weight fabric, featuring ClimaSense Thermoregulation Technology that automatically adjusts to your body temperature. It does this be trapping air to maintain warmth when your body starts to cool down. When your aerobic activity increases and your skin temperature rises, the fabric allows moisture vapor to escape to maintain comfort. Whether skiing, mountaineering, fat biking, snowshoeing or winter running, Thermolator is functional performance at its best!