The Thermolator 2.0 Kids Thermolator Performance Pants is the ideal thermal piece for all day warmth and comfort while being out in the elements. These versatile long johns feature an ultra-soft, midweight fabric utilizing Terramar's features 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.