Offering three-stage warmth technology, Heat Holders Unisex Big-Foot Thermal Extra-Large Crew Socks boast a 2.34 Thermal Overall Grade (TOG) rating, making them seven times warmer than everyday cotton socks that offer a 0.33 TOG rating. Breathable Heat Holders Yarn provides high-performance insulation to block out the cold, while offering superior moisture-breathing abilities so your feet stay dry. Heat Holders Loops an innovative knitting technology that produces a unique, extra-long-loop cushion pile hold warm air in. Heat Holders Brushing process maximizes the amount of warm air held inside the socks for continued all-day comfort and warmth. 91% acrylic/5% nylon/3% polyester/1% elastane. One size fits most. Imported. Mens size range: 7-12 and 13-15. Womens size range: 7-13 and 14-16. Colors: Black, Charcoal, Denim, Navy, Stonewash. Type: Socks.