Extra Warmth & Dryness Next- to-Skin. Thermal: Natural warmth generated by Endurofil™ microfibre yarns. Liner: Baselayer for under socks. Moisture wicking microfibres knit against the skin trap warm air, keeping feet warm and dry. Recommended to be worn under other Bridgedale socks in extreme conditions. Fibre Content: 79% Endurofil™/polypropylene 17% Nylon/polyamide 4% Lycra®/elastane