25mm (1 inch) adapter is compatible with Garmin GPS and other devices with a 17mm mounting pattern</br>Adapter fits onto Arkon Robust Mounts or RAM Mounts that feature the 25mm ball pattern</br>Adapter fits onto 25mm mount head or base</br>2 year limited warranty</br><br/>http://www.amazon.co.uk/gp/product/B01MZXRSST