72% Coolmax, 26% nylon, 2% spandex * Size small is thorlo sock size 9 which fits women"s shoe sizes 5-6.5- see size chart under images * Spandex and Thorlon in the top provide more stretch so socks don"t creep down leg and cause bunching * Midweight padding at instep and over shin to reduce lace pad and boot pressure * Wash and dry inside out (to fluff up the pads) using liquid fabric softener after each use (to lubricate the fibers for longer life). Liquid fabric softeners critical to receive full benefit of the product design