All Metal Construction: This robust CNC Machined aluminum bar mount base provides the ultimate hold and long-lasting usability for a variety of bar shapes. Bar Compatibility: This bar clamp is designed to securely hold onto various bar shapes and styles, with a minimum bar size of 3/8” and a maximum bar size of 5/8”. Excellent solution for mounting onto headrest bars, crossbars, and mirror bars. Easy Installation: Four self-tightening bolts with L-wrench included in the box allow for simple and swift installation. Featuring Type-B Interface: Tackform's standardized method for attaching a ball to mounting surfaces is Type-B which enables easy switching between ball sizes and dovetails for cross-platform compatibility. The dovetail connection is ideal for short-reach applications, while the 20mm ball is typically preferred for longer reach applications. Type-B makes swapping your ball connection quick and easy. Tackform 20 Series: Specifically designed for compatibility with Tackform’s DuraLock™ 20 Series Platform, revolving around the 20mm ball and socket system. While compatible with other 20mm products, our parts stand out for their tested durability and engineered load capacities, featuring a safety factor not guaranteed by other manufacturers.