This is a must have if you tow multiple trailers. I've had the complete kit version for years which includes 1 7/8", 2", and 2 5/16" balls. I just purchased a new trailer that required a taller ball mount, but I'm keeping my old one as well, so I purchased this smaller set so that I had the same setup on both mounts. Now I have a tall and short ball mount with interchangeable ball sizes, so I can town almost any trailer I need to.