These are the finest socks of there kind on the market today. Made of a special blend of nylon and lycra spandex. They are both waterproof and breathable. These socks have a waterproof middle layer that allows perspiration to escape but water will not penetrate. The inside layer is made of Dupont Coolmax yarn that provides a soft flexible, stretch to fit sock. This seamless design provides the ultimate in action performance and comfort. Available in size medium or large.