1000 Mile Trainer Liners - SS19 Double-layer construction - Eliminates friction on the skin and reduces wear. Tactel inner layer - Wicks sweat to the moisture-absorbing outer layer, keeping you comfy and dry. Top venting - For increased breathability. Arch bracing and a Y-heel - Improve support and create a customised fit. HeelPower design - Grips the heel firmly in place to reduce slippage.