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. For protecting your Switch Ball trailer ball shank when not in use, the CURT rubber trailer ball cover is a perfect fit. This cover is designed to fit Switch Ball shanks with a 1" neck diameter and 3/4" threaded shank. Material: Steel.