Heat Holders Twist Crew Sock 91 % Acrylic, 5% Nylon, 3% Polyester, 1% Elastane Imported Keep feet warm on the coldest of days and pull on this pair of Heat Holders for men, the ultimate thermal sock! Heat Holders are made from a specially developed heavy bulk yarn which has extreme thermal qualities. The specially developed advanced fibers provide high performance insulation against cold with superior moisture wicking abilities. The innovative long looped thermal pile knitting technology products a unique, extra-long looped cushion pile to hold in more warm air, increasing the thermal TOG rating. Using an intense brushing process produces a soft brushed inner fabric that maximizes the amount of warm air held inside the socks for all-day warmth and comfort.