Brackets fasten to horizontal tube assembly using metal screws. Drilling required to fasten and locate Brackets. One pair of Z Brackets and fasteners included in package. Sliding Bolts in aluminum extrusion on Arrow Stick fasten to holes in Brackets. Arrow Stick sits just above horizontal tube assembly just behind the Backrack. Suitable for Backrack or Safety Rack. Compatible with 91002, 91002 REC, 91006.