These 1000 Mile Trainer Liner Socks are designed to protect your feet and prevent blisters. The Tactel® inner layer stays with the foot, wicking away moisture, whilst the outer layer moves with the shoe. The lack of friction between the layers helps prevent blisters and reduces wear. Features include top venting for superior breathability and arch support for extra stability. They also incorporate Heel Power technology. Sizing is based on UK shoe size. Fabric composition: Outer layer: 54% Cotton, 44% Nylon & 2% Lycra. Inner Layer: 100% Tactel®.