FoxRiver 02 Plus Compression Over the Calf Socks 67% Polypropylene, 28% Nylon, 5% Spandex Made in US Sizing: Medium (Shoe Sizes: Men's 6-8.5; Women's 7-9.5); Large (Shoe Sizes: Men's 9-11.5; Women's 10-12.5) URfit System (Ultimate Response Fit System) Sentry technology resists odor in the sock Fights fatigue by increasing blood flow up from ankle with 15-20 mmHg of graduated compression Sizing: Medium (Shoe Sizes: Men's 6-8.5; Women's 7-9.5); Large (Shoe Sizes: Men's 9-11.5; Women's 10-12.5)