Tite-Lok Tl-2002 Truck Cap Topper Mounting Clamp (4 Pack) Designed For Mounting Truck Caps Or Covers With Fiberglass Or Aluminum Rails C-clamps help you secure a hard tonneau cover or camper shell to the side rails of your pickup truck bed No-drill installation - Place clamp around bed rail and truck topper - Tighten included carriage bolt Durable, rustproof Aluminum construction Fits multiple makes and models