The 1000 Mile All Terrain Sock has a unique double layer construction to offer maximum comfort with no blisters The high wicking inner Tactel layer stays with your foot while the soft wool-mix outer layer moves with your footwear in order to reduce friction & thus prevent blisters & reduce wear of the sock The unique combination of fibres maintains a comfortable temperature for the foot Arch braces on both layers help prevent unwanted movement even on severe slopes