SockGuy IPA Wool Crew 6IN Cycling Sock Shrink-resistant and itch-free; made from 75% TURBOwool, a superior blend of 50% polypropylene and 50% merino wool TURBOwool Deluxe Wool Blend is 5 times stronger than merino wool alone Easy fit cuff features a non-binding cuff Stretch-to-fit, 2 size system Year-round performance: warmer in winter, cooler in summer