Choosing the best ball mount for your vehicle establishes a level of connection between the towing vehicle and the trailer. To select the best ball mount, figure out your hitch height from the top of the hitch receiver of your vehicle to the ground. Figure out your coupler height by leveling the trailer and measuring from the bottom of the coupler to the ground. Then find the difference between the hitch height and the coupler height to determine the amount of ball mount that you need. A ball mount with a drop is ideal if the coupler height is lower than the hitch height. A ball mount with a rise will be suitable if the hitch height is lower than the coupler height.