*** This double ball joiner is made of high quality aluminum raw material, it is sturdy and durable. | *** This dual ball holder is from 25.4mm (1 inch) ball head to 25.4mm (1 inch) ball head, compatible with RAM Mounts 25.4mm to 25.4mm socket arms. | *** The length of this bullet adapter is 2.5 inches from one end to the other, it is used for GPS device extension. | *** This 1" to 1" dual ball mount can be used for Garmin GPS and bike phone holders and other 1"/25.4mm/RAM B-size industry standard socket mount. | *** With this dual ball adapter mounting kit, you can rotate your Gamin GPS, camera mount or phone holder device 360°, it is suitable for outdoor riding and photo shooting.