An extremely high Thermal Overall Grade (TOG) of 2.34, this thermal sock is 7 times warmer than a basic cotton 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 inside of each sock has been intensively brushed so it not only feels sensationally soft, but also traps warm air close to the skin, keeping your feet warmer for longer and for all-day warmth and comfort. Content: 91% Acrylic, 5% Nylon, 3% Polyester, 1% Elastane. Weight: Heavyweight.