If you've already got a socket arm, you can easily use this universal holder to safely attach a GPS device or splash-proof caseThe holder, consisting of a ball joint with 1'' diameter and mounting plate, is made of very strong fiberglass-reinforced plasticThe hole pattern of the universal holder is consistent with the standard hole pattern of the device socket of the TOMTOM Rider and Garmin zumo modelsIncluded in delivery1 x 1'' ball with mounting plateMounting instructions