The RV Bumper Receiver Adapter from Buyers Products is ideal for adding a bike rack, cargo carrier, or other cargo accessory to the back of your RV. The adapter clamps onto a 4 in. or 4-1/2 in. square RV bumper and accepts 2 in. accessories. It includes durable zinc-plated hardware. This receiver adapter cannot be used for towing. Do not install on decorative aluminum RV bumper covers. Assembly required.