The ball mount is designed to be inserted into the hitch. Ball Mounts come in different lengths and are used in drop and rise positions, Try and determine which ball mount fits your needs. When selecting a ball mount make sure to look at the weight rating, it should be equal to or larger than the hitch being used. For safe and comfortable towing the trailer should always be set up to tow on a level plane. Sometimes a trailer's tongue is higher or lower than the ball mount on the vehicle. In this situation a ball mount with a "Rise" or a "Drop" is required to level the trailer.
Class I & II ball mounts are also referred to as drawbars. The drawbar typically comes with the hitch because the hitch is designed with a specific drawbar in mind for each vehicle. Refer to your hitch installation instructions for any replacement drawbar.
Class III through V hitches are designed with many different ball mounts in mind because of the variety of SUV and truck suspensions and tire combinations.