Low voltage rings are used to cut TV and cable connections into a wall. These rings are made of either plastic or metal. Some come with bend-in tabs that wrap around the drywall for an easy installation. Others have turn-out tabs that lock the ring into place against the drywall. Yet others have slide-on mounting brackets that tighten the ring to the drywall.
In order to install these rings, you'll need to cut a hole using a drywall saw or jigsaw. Simply mark the wall with the inside dimensions of the ring and cut slightly larger than the marked hole. The ring should still cover the hole when you are finished.
Insert the ring into the hole and either bend over the tabs, tighten the set screws, or push the retaining brackets into place. Level the ring and you're ready to install a low voltage device. These rings should never be used to install things like switches and outlets. The name of the ring says it all, it is intended for low voltage devices only!