BackRack 99-16 Superduty Steel Body Only Low Profile 21in Drill Hardware KitOur new LOW PROFILE DRILL Hardware Kit is available for select late model fullsize trucks. These require you to drill two holes through the top of the bed rail for installation. If you must have the Toolbox sitting at bed rail height this is the option. Four carriage head bolts secure the assembly allowing you to place the Toolbox at a low profile using existing clamps that came with the Toolbox. Drill if you must. Not compatible with TONNEAU COVER