Base layers have emerged as a must-have item when temperatures are on the low side. They trap in heat and regulate your body temperature to keep you warm and comfortable. A base layer is the layer closest to the skin and acts as a second skin to provide vital warmth throughout the day. The ergonomic design of the CG Armour Fitted Mock Base Layer keeps seems off of high abrasion areas for comfort and high durability. The CG (ColdGear technology) holds in body heat exceptionally well.