Comfortable and hard-wearing thermal socks from Heat Holders. Heat holders are made from a specially made heavy bulk yarn which keeps your feet insulated and comfortable. Featuring a long fit, reinforced heel and toe and a brushed, super soft inner that traps warm air close to the skin, keeping you warmer for longer. Made from 91% Acrylic, 5% Nylon, 3% Polyester, 1% Elastane.