Wrightsock Women's Coolmesh Crew Socks Inner: 70% Polyester, 30% Nylon; Outer: 71% Polyester, 24% Nylon, 5% Lycra Machine Wash Double-layer crew sock three-pack Outer layer is constructed of performance fibers. Inner layer is smooth, undyed, hydrophobic moisture-wicking fabric The interaction between layers absorbs friction to prevent blisters Two layers trap air for insulation from heat and cold