SockGuy Trail Maint Wool Crew Cycling/Running Socks 100% Cotton Uses the Stretch-to-Fit&trade; sizing system and Easy-Fit&trade; cuff to create the perfect fit and eliminate blisters Year-round performance: keeping you warmer in the winter, cooler in the summer 75% TURBOwool, a blend of 50% Merino Wool and 50% Polypropylene Shrink-resistant & itch-free