The tight weave of Therma-FIT fleece works like a favorite blanket because it keeps the body warm and is soft to the touch. It's also lightweight, has stretch, and dries quickly. This technology is designed from a densely constructed weave that is brushed on both sides to create air pockets. These air pockets in the fabric trap and retain body heat, but not moisture. This creates a garment that is not as bulky as other thermal fabrics and delivers greater warmth and wind resistance.