The warmest, softest, longest lasting alpaca socks we've ever produced. They are cushion looped, a fantastic fit and very durable. A gentle elastication around the arch of the foot ensures that they won't slip down inside your boots. They are genuine knee socks, not 3/4 length. Made with a supersoft Baby Alpaca wool blend. One Size: 37-41 (UK size 5-8) (US Size 6.5 - 9.5) They contain the necessary amount of elastane and nylon to make them last. 45% Baby Alpaca, 40% Acrylic, 15 % Nylon. A higher ratio of alpaca would not be as durable.