Transition: 1cm=10mm=0.39inch
Please allow 1-3mm error due to manual measurement.
Please make sure you don't mind before you bid.
Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thanks very much!

This ball mount holder ball adapter rotated from 1 inch ball head to 0.67 inch ball head.
This dual ballpoint pen is compatible with RAM/iMESTOU B ball foot arm systems.
It is a mounting kit for universal use, such as bike phone holder, camera mount, special gear extension and transmission.
With this dual ball adapter you can rotate your device 360°. It converts a 1-inch/RAM B size/25mm mounting socket system to a 17mm mounting socket.
It is used for Gamin GPS, bike phone holder, motorcycle phone mount or any other 17mm GPS mount socket.