The rear-view mirror frame 1 inch (approximately 2.5 cm) ball holder base can accommodate mirror rods with a diameter of 0.39 inches (approximately 1.9 cm) to 0.63 inches (approximately 1.6 cm). The circular rail adapter for motorcycle rearview mirror frames and mini handlebars is equipped with three sizes of rubber ring inserts to provide a tight fit and protect the mounting surface. Rubber ring pad diameter: 0.5 inch / 0.87 inch / 1 inch. The aluminum alloy mounting base uses rubber inserts and locks to prevent high vibration from loosening. It is used to install to the rearview mirror frame and the motorcycle and bicycle mini handles and other circular rails within the specified size. This 2.54 cm ball seat is made of 6061-T6 aluminum alloy, which is durable and reliable in harsh environments. The ball adopts TPU molding design, which has anti-slip performance. The 1-inch (about 2.5 cm) tee base is compatible with RAM mounting, dual socket arms and other mobile phone holders with 1-inch (about 2.5 cm) tee systems. Suitable for bicycles, motorcycles, mountain bikes, electric scooters, ATVs, etc. Colour: black Material: aluminum alloy + plastic Package Contents: 1 * Navigation mounting bracket Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm. Note: 1. Please allow 1-3 mm error due to manual measurement and 1-3g weight error make sure you don't mind before ordering. 2. Due to the lighting of the photos and the difference of monitors, the pictures may not reflect the actual color of the real item. Please make sure you don't mind before ordering, thank you! About Shipping: 1.please pay attention to your delivery address such as: name, street, house number, doorbell/email without name, etc. is correct, or the order will not be delivered correctly. 2.All items will be shipped within 3 business days after the payment is received. Most times you will receive them within 8-12 days then. The specific delivery time is depend on circumstances. 3.During the shopping process, if you have any questions, please feel free to consult us, we will reply you within 24 hours Hope you have a pleasant shopping experience!