Vibram Men's and Women's Five Fingers Rubber Rubber sole Seamless 2mm Footbed Insole - stitching free, to reduce friction and improve comfort Heel and Instep Hook and Loop Closures - helps pull the upper tight round the contours of your feet so it feels like a second skin 4mm Vibram TC1 Performance Rubber Outsole - offers excellent grip, traction and protection for all cross training activities