The RAP-300U, RAM® Magnetic Power Plate™ II, is designed to hold various devices including radar detectors and cellphones. The magnetic plate includes one powerful rare earth magnet, rubber cradle and two adhesive metal plates (one 1.5" x 2" rectangle plate, one .75" round plate). To mount your device to the magnet, you will need to attach one of the metal plates to the back of you device.