Heat Holders Men's No1 Thermal Socks Black 7-12 Us 91% Acrylic 5% Nylon 3% Polyester 1% Elastane machine washable Thick, chunky and with a massive tog rating of 2.34 for warmth Heat Holders are made from a specially developed heavy bulk yarn which has extreme thermal qualities Brushed inside to hold heat within without sweating - mid calf length Ideal inside boots and for anyone who works outside -gentle grip tops An ideal Gift- Women's and children's versions in my Amazon shop