What is the plate on my XL for?
When installed correctly, the plate keeps the locking nut of the XL flush with the coupler, which in turn reduces the possibility of damage on the coupler should the XL pivot due to excess horizontal force. Install the plate by placing it under the ball before threading the ball into the cradle on the XL. The lip of the plate preferably faces the back of the coupler. It can be reversed if necessary to achieve a tight fit. Review these visual instructions if you need further help in using your plate.