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\" and ball capacity of 3,500 lbs. Ball 2 has a 2\" ball diameter and a ball capacity of 6,000 lbs. The shank measures 2-1/4\" long and 3/4\" in diameter. We construct these interchangeable hitch balls from premium-grade steel for strength and give them a bright nickel-chrome finish for a long life. To ensure your safety and provide you with a tow ball you can depend on, CURT Switch Balls are independently tested in accordance with SAE J684.