Our new modular bed rack gives you the freedom to adjust 3 of the top rails to any position to fit whatever accessories you are wanting to mount, as well as sliding all the way forward to give to access to the bed to load large appliances, quads, and dirt bikes without removing the rack for your truck. Each of the 3 crossbars has 4 hand turn knobs to tighten once the cross bar is in its desired position. The crossbars slide on a machined Delrin insert along the 80-20 aluminum extrusion. The entire top portion of the rack is constructed of 80-20 aluminum extrusion. We chose to go with 80-20 because of its versatility. The T slot design allows the end user to fit an infinite amount of accessories by simply adding additional threaded T slot framing nuts. The base is constructed out of 3/16 inch steel with holes cut into the side to mount to factory Toyota bed rails This entire rack is bolt together for easy storage when not in use as well as making for an easier assembly process. Each rack goes with 2 full lengh side mounts to mount accesories like Rotopax or Maxtrax tire skids.