RV Bumper Adapter gives you a 2" receiver for mounting bike racks. Bolt this receiver to the underside of your 4" square continuous-weld steel tube bumper to create a 2" x 2" trailer hitch receiver opening. Note: For use with hitch-mounted, RV-approved accessories only. Not rated for towing. Zinc-plated hardware included Sturdy steel construction | Swagman RV 4" Bumper Adapter