Fox River Knee-High Ultra Lightweight Merino Wool Socks - Women's 62% Merino wool, 36% nylon, 2% spandex. Hecho en USA Memory-knit construction holds form, wash after wash. Contoured rib top holds sock in place to eliminate slippage. Spandex compression zones add support and keep sock in place all day long. Reinforced toe and heel add comfort and extend sock life. Smooth, flat toe seams add comfort and durability