Use as a blister-preventing base layer under a traditional thick walking sock for 4 season use or as a stand-alone summer sock with lightweight fabric boots 1000 Mile Ultimate Liner Sock is a double layer sock: the inner layer wicks away perspiration to the moisture absorbing outer layer, keeping the feet dry Combination of fibres, including the latest REPREVE recycled yarns, and top venting maintains a comfortable temperature for the foot bracing offers additional support fabric technology grips the heel firmly in place ,so no slippage!