Your review: The metal of the wall box, into which this heater is screwed is too thin. The whole unit will wobble if only 2 screws are used - and there are only 2 holes in the box for mounting purposes. Had to drill a third at rear of box to stop the wobble.
Install was straight forward and the heater has worked great during the 2 weeks I've had it in my workshop. DON'T buy the non-returnable extender. It is not needed and does not properly fit this heater.