The 1000 Mile Ultimate Lightweight Walking sock is a sock within a sock.  Perfect for trudging around the countryside or long days in the city.  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.  Suitable for 3 season walking in any boot.  Arch bracing for additional support.  The unique combination of fibres maintains a comfortable temperature for the foot. (06/11) Covered by The 1000 Mile Guarantee!  Double layer construction eliminates friction between shoe and sock, thus reducing friction between sock and foot,  The skin should therefore not be rubbed by the socks, meaning no wear out for 1000 mile of use and  no blisters.  Money back or replacement if, within one year from date of purchase, either you experience blisters or the socks wear out within 1000 miles, provided care instructions have been followed and socks are returned with original receipt.