For all-day comfort and total warmth, the Heat Holders Crew Socks feature innovative knitting technology that produces a unique, extra-long looped cushion pile to hold in warm air, increase the TOG rating and provide moisture management. Made of 91% acrylic, 5% nylon, 3% polyester and 1% elastane thermal yarn for stretchy, comfortable wear. Heat Holders Men's Socks Black, Large - Western And Thermal Socks at Academy Sports