Metal ring (magnetic plate)
A metal ring, sometimes called a magnetic plate, is a thin adhesive metal ring stuck to the back of a phone or case so that a phone without MagSafe can attach to a magnetic mount.
Every SSUCTION mount comes with a round metal ring in the box. Stick it in the middle of the back of the phone or case, not near the camera. Apple advises keeping magnets and magnetisable metal away from the rear camera, because they can interfere with optical image stabilisation.