Superior cushioning and performance These NEW Eco-friendly socks have been sustainably manufactured using our latest BCool fibre. Each sock is specifically constructed to the contour lines of the left and right foot, allowing for the perfect anatomical fit. When using a size up running shoe, this medium cushioned sock will assist with filling the space to prevent foot movement in the shoe and have that second-skin fit. The heel tab is for added comfort, preventing chafing while keeping the sock in place.