DexShell Waterproof Breathable Thermlite Merino Wool Socks 24% nylon Imported Outer: 96% Nylon, 3% Elastane, 1% Cuff Elastics Interlining: 100% Waterproof and Windproof Porelle(R) Membrane Inner: 38% Merino wool, 38% Anti-pilling acrylic, 24% Nylon Over-ankle length Seamless construction for the highest comfort Outer: 96% Nylon, 3% Elastane, 1% Cuff Elastics Interlining: 100% Waterproof and Windproof PorelleMembrane Inner: 38% Merino wool, 38% Anti-pilling acrylic, 24% Nylon Over-ankle length Seamless construction for the highest comfort Small -  Men 4-6     (Women 5-7) Medium - Men 6.5-9   (Women 7.5-10) Large -  Men 9.5-12   (Women 10.5-13) XL -     Men 12.5-14.5