MIDWEIGHT BASE LAYER - The Hot Chillys Youth Micro-Elite Chamois Tights are the perfect thermal underlayer to keep kids warm, dry, and comfortable so they can have fun; Cozy comfort and superior performance make these thermal bottoms for boys and girls an essential cold weather gear for young athletes; With their fit and flexibility, active kids stay warm and dry no matter the conditions MOISTURE TRANSFER FIBERS - The Hot Chillys base layer tights are designed for warmth, performance (including but not limited to breathability and moisture management), and wearable comfort; An essential feature in all Hot Chillys winter underwear is exclusive moisture transfer fibers (MTF) that move moisture away from the body by employing hydrophobic yarns to wick away perspiration, thereby keeping your child dry and comfortable BODY FIT & UPF 30+ PROTECTION - Designed with 4-way stretch, these children's winter tights hug the body for a next-to-skin fit, enhancing breathability and moisture management; Body fit garments move with your child, eliminating extra bulk and allowing a full range of motion while staying against the skin; In addition, the Micro-Elite Chamois thermal base layer has UPF 30 protection WARMTH FACTOR 8/10 - Ranked from Mild to Hot, the Warmth Factor Thermometer tells you how warm is Hot Chillys thermal clothing; Warmth Factors 6, 7, and 8 are considered Midweight and are very popular for most cold-weather activities; The Micro-Elite Chamois thermal pants for kids have a warmth factor 8 out of 10; These underwear bottoms feature a smooth face for easy layering and a soft fuzzy interior for extra warmth without adding bulk BIO-SILVER AND ACTIVATED CARBON - Bio-Silver ions have been intimately blended into some of Hot Chillys yarns to help your children stay fresh; These natural, silver-based properties remain active for the lifetime of the fabric; In addition, activated carbon incorporated into the yarns enhance thermal regulation and smell-blocking characteristics of the Hot Chillys thermal underwear for kids