Hitch Accessory 3: Adapters and Extenders
Many hitch-mounted accessories require additional equipment. For example, if the shank of a ball mount or other accessory doesn't fit the size of the receiver tube on a hitch, then you can use an adapter to ensure compatibility. Some adapters increase the size of the receiver (1.25-inch to 2-inch adapters, or 3.2 centimeters to 5.1 centimeters), while others decrease the size of the receiver (2-inch to 1.25-inch adapters).
A hitch extender increases the clearance for a hitch-mounted accessory. Extenders are necessary if your vehicle has a large, rear-mounted spare tire or a camper shell that overhangs the rear bumper. Even if your vehicle doesn't have a camper or rear-mounted spare, an extender may be necessary if your hitch is located well underneath the bumper. In essence, an extender moves the hitch receiver forward an additional 6 to 12 inches (15 centimeters to 31 centimeters). With the extra clearance, it's possible to use accessories such as a bike rack or a cargo carrier.
Only two hitch accessories left. What's the next one going to be?