Features of the Smartwool Women's PhD Pro Endurance Printed Crew Sock Indestructawool Technology for enhanced durability Minimal and targeted sole and Achilles cushion to add protection without adding bulk Malleoulus ankle cushion for protection on the most rugged trails 4 Degree elite Fit system for a dialed, Performance-oriented Fit Shred shield Technology reduces wear from toes Virtually seamless toe for enhanced comfort Fabric Details 49% Merino Wool, 44% Nylon, 4% Elastane, 3% Polyester