When the trailer departs, the lip drops automatically behind the face of the bumpers. Concrete recess is not required. It comes complete with bumpers and installation instructions. Standard ramping is 27", with a 36" long ramping length available for smaller grade. A steel dock edge, or approach ramp is required for proper installation. Operated by placing the actuation handle into the pocket of the inner lip and pulling down toward the floor. The operator then pushes the handle forward until the lip rests on the truck bed. As the trailer departs, the lip retracts behind the bumper face automatically.