Mopar« Skid Resistor (2X`s more skid resistance) Under-the-Rail Bed Liners and Tailgate Covers are custom tailored to your truck`s box. Tailgate Covers feature built-in cup holders. Molded of a blend of rubber and polyethylene, with a skid resistant surface and ribbed design that promotes drainage of water from the bed. Mopar Under-the-Rail Bed Liners provide full use of the integrated verticle and horizontal board dividers..