Our Kids Original Long Leg Thermal Socks in Royal Blue are sure to keep their feet warm on even the coldest days - offering the same trusted warmth and comfort as our famous Original thermal socks with an extra-long leg, perfect for wellington boots. These thermal children's socks are perfect for keeping them cosy all winter long. So whenever they need maximum cold-weather protection with reliable comfort in your boots or wellingtons, our Original long length thermal socks will make their life warmer. Fibre Composition: 91% Acrylic, 5% Nylon, 3% Polyester, 1% Elastane. Machine Washable at 40°C. Heat Holders can be tumble dried but are happiest when line dried.