Amazon.com: TOPTOW 63800 RV Bumper Hitch Receiver Adapter 2 inch for 4 inch X 4 inch and 4.5 inch X 4.5 inch Bumpers, Fits for Bike Racks, Cargo Carriers Camper-on : Automotive
Amazon.com: VOWAGH 2 Inch RV Bumper Hitch Receiver Adapter Compatible with RV Bumper Bike Rack Cargo Travel Carrier Mount Built for 4" x 4" Continuous Welded Steel Bumpers : Automotive
CURT RV Bumper Hitch with 2" Receiver (Fits 4" x 4" Bumper Beams) 19100 - The Home Depot
HiTow RV Bumper Bike Rack Carrier Hitch Receiver Adapter for 4" Square RV Bumpers Bike Cargo Coachman