Double layer (hidden profile) trainer liner: tactel inner lining sock helps prevent blisters and to keep the foot dry and cool Top venting for improved breathability Mid-foot arch brace for support with heelpower to prevent the sock from slipping Great for running, gym work and all other foms of training as well as everyday wear Outer sock: 76% cotton, 22% nylon, 2% elastane, 1% lycra. inner sock; 100% tactel