2007+ Silverado/Sierra Low Profile 21" Drill Hardware Kit (BCK30119LP)Description This Low Profile Drill Hardware Kit mounts a BackRack at bed rail height on select late model fullsize trucks. Four carriage head bolts secure the assembly using the existing clamps, letting you place a toolbox at a low profile. Requires drilling two holes through the top of the bed rail. Features Low profile mounting at bed rail height Four carriage head bolts for a secure hold Uses existing toolbox clamps Requires drilling two holes