The rear-view mirror frame features a 1-inch ball holder base that accommodates mirror rods with diameters ranging from 0.39 inches to 0.63 inches. The circular rail adapter for motorcycle rearview mirror frames and mini handlebars includes three sizes of rubber ring inserts to ensure a secure fit and protect the mounting surface. Rubber ring pad diameters: 0.5 inch / 0.87 inch / 1 inch. The aluminum alloy mounting base uses rubber inserts and locking mechanisms to resist loosening caused by vibration. It is designed for installation on rearview mirror frames, motorcycle and bicycle mini handlebars, and other circular rails within the specified size range. This 2.54 cm ball seat is constructed from 6061-T6 aluminum alloy for durability and reliability in demanding conditions. The ball features a TPU molding design for enhanced grip. The 1-inch tee base is compatible with RAM mounting systems, dual socket arms, and other 1-inch tee-compatible mobile phone holders. Suitable for bicycles, motorcycles, mountain bikes, electric scooters, and ATVs. Color: black Material: aluminum alloy + plastic Package Contents: 1 × Navigation mounting bracket Note: Color may vary slightly due to screen settings and lighting conditions. Measurement tolerance: ±1–3 cm.