Wrightsock Women's Running Ii Qtr 3 Pack Athletic Socks Inner: 70% Polyester, 26% Nylon, 4% Lycra Spandex; Outer: 68% Polyester, 24% Nylon, 8% Lycra Spandex Machine Wash New contoured shape and fit Stabilizer zone to help lock the sock in place Improved moisture management Increased durability Two layers trap air for effective insulation from heat and cold