Second Wind Compression Sock Performance Enhancing Graduated Compression improves circulation for faster recovery. Reduces muscle vibrations for better endurance & less fatigue Seam free toe eliminates irritating ridge for more comfort Microfiber nylon for soft, durable, moisture wicking fabric Mesh venting for increased breathability and ventilation 'Y&'; heel gore for better contoured fit Arch Support band keeps sock in place for better fit Double Welt turned top for comfort and stay up Light strategic cushioning for zone shock absorption 85% Nylon 14%Spandex 1%Polyester Sock Size S M L XL Calf Circumference 10.25" - 12.5" 12.5" - 14" 14" - 17" 17" - 20" Men&';s Shoe up to 6 6.5 - 8.5 9 - 11.5 12+ Women&';s Shoe 5 - 7.5 8 - 10 10.5 - 13 13.5+