? This aluminum alloy 1'' ball mount base compatible with RAM Mounts & BRCOVAN any B size 1 inch ball double socket arms. ? Main body made of 6061-T6 aluminum alloy for durability and reliability in the most demanding environments. CNC integral molding, solid structure. Anodized surface treatment, smooth surface, durable. TPU over-molded ball head, non-slip and wear-resistant. ? The handlebar ball mount utilizes rubber-insert and lock-bolt to prevent loosening in high vibration for mounting to motorcycle rear-view mirror as well as other mini round rails within the stated dimensions. An Allen key is included with the package to facilitate your installation. ? Package comes with three rubber ring inserts to provide a snug fit and protection of the mounting surface. Rubber ring pads diameter: 0.39''(10mm), 0.47''(12mm), 0.55''(14mm). You can add or remove them depending on the size of the rails. When the rubber ring inserts is not embedded, the diameter of the mounting base is 0.63'' (16mm). ? This 1'' ball mini clamp mount accommodates round rails 0.39''(10mm) / 0.47''(12mm) / 0.55''(14mm) / 0.63''(16mm) in diameter.