CURT Switch Ball trailer balls are a breakthrough in trailer ball technology. As a result of CURT innovation and engineering genius, Switch Balls offer the ultimate in convenience and reliability for a variety of light-duty and medium-duty towing applications. Essentially, a CURT Switch Ball is a trailer ball shank with a removable head. With its exclusive J-groove design, the Switch Ball trailer ball allows different heads or ball sizes to be places on the shank for accommodating different coupler sizes. This means there is no need to switch between ball mounts or even to own a second ball mount to fit an additional trailer. When you need to make the switch, simply twist the Switch Ball head, lift it off and twist on another. The J-groove ensures a solid hold on your trailer, while still allowing for easy removal of the trailer ball without tools or pins. This CURT Switch Ball trailer ball set comes with two ball attachments. Ball 1 features a ball diameter of 1-7/8 Inch and ball capacity of 3,500 Pound. Ball 2 has a 2 Inch ball diameter and a ball capacity of 6,000 Pound. Ball 3 has a 2-5/16 Inch diameter and a ball capacity of 8,000 Pound.