MIDWEIGHT BASE LAYER AND MOISTURE TRANSFER FIBERS -designed for warmth, and wearable. Hot Chillys moisture transfer fibers move moisture away from your body by employing hydrophobic yarns to wick away perspiration, thereby keeping you dry and comfortable. BODY FIT AND UPF 30+ - Designed with 4-way stretch, these fabrics it’s for a next-to-skin fit, enhancing breathability and moisture management. Ultraviolet Protection Factor. Sunlight includes rays of ultraviolet (UV) radiation. WARMTH FACTOR 8/10 - Warmth Factors 6, 7, and 8 are considered Midweight and are very popular for most cold-weather activities. 4-WAY STRETCH - Fabrics with this elastic feature will remove extra bulk, providing a full range of motion, and improving performance. BIO-SILVER AND ACTIVATED CARBON - Bio-Silver ions have been intimately blended to help stay fresh. These natural, silver-based properties remain active for the lifetime of the fabric. Activated carbon incorporated into the yarns enhance thermal regulation and odor-blocking characteristics of this product.