This is an Extreme Thermal Sock. Get maximum thermal retention for your feet from 68-70% Alpaca fiber surrounding your feet warm on those winter days. Available in Gray and in 5 sizes (S-XXL) Small - Women’s 5-8 Men’s 4-7 Medium - Women’s 8-10 Men’s 7-9 Large - Women’s 10-12 Men’s 9-11 X Large - Men’s 11-14 XX Large - Men’s 14+