Big Discount RV

The Length is the distance from the center of the ball hole to the center of the pin hole.
The Drop is the distance from the top of the shank to the top of the ball platform.
The Rise is the distance from the top of the shank to the top of the ball platform.

Trailer Ball Mounts -Various Styles and Ratings

The trailer ball mount should be appropriate for your towing application. You should always measure for the proper selection. A light weight Class II ball mount might be rated for a trailer up to 3000-3500 lbs and would generally fit a 1 1/4" square receiver hitch. A Class III ball mount might be rated for trailer weights of about 5000 lbs and a hitch weight of about 500 lbs. Class IV and Class V ball mounts would have even higher rated capacities. You should always measure and use a ball mount with the proper rating for your application.

For best towing, always set up to tow on a level plane.