Men's Lasso Sizing (Men's US Shoe Size): Medium: 7-10 Large: 10-13 X-Large: 14-17 Women's Lasso Sizing (Women's US Shoe Size): Small: 5-9 Medium: 10-13 Youth Lasso Sizing (US Men's Shoe Size): Youth: 6-8 (European Sizes Start at 39 for Men and 35 for Women)