Simple thermostat wall trim plates

rather simple cover plate design.. it's made for when you have a double box, with a single adaptor plate to mount a single thermostat or some such thing to the box.

it's a slip over and trap in place, not a screw in/on, so not for standard wall switch or outlet coverage. Though you could use it under a standard plate to get the extra coverage if there was damage to the wall around the box and need to cover more...