The 100% Tactel® inner stays with the foot, wicking away moisture, whilst the soft wool-mix outer layer moves with the shoe. The lack of friction between the layers helps to prevent blisters and reduces wear. With the unique combination of merino wool outer layer and the Tactel® inner layer helps to maintain a comfortable temperature for the foot. New design with HeelPower grips the heel keeping the sock firmly in place and helping to reduce irritation on the skin. Ideal for 3 season walking in all boots. The 1000mile Ultimate Lightweight Walk Sock has a 100% Tactel inner layer that stays with the foot helping to wick away moisture and keep the foot dry whilst the soft merino wool-mix outer layer moves with the shoe. The lack of friction between the layers helps to prevent blisters and reduce wear. recommended for 3 season walking in any type of boot tactel inner layer wicks moisture from the foot 2 layer sock helps to reduce friction, prevent blisters & reduce wear arch bracing provides additional support outer layer: 63% merino wool 34% nylon 3% lycra, inner layer: 100% tactel Tactile inner layer wicks away perspiration to keep the feet cool and dry Arch braced for extra support Heel Power technology - keeps the sock firmly in place! Men's and Ladies fit - sizing by UK shoe size