Made by The Hoyt Electrical Instrument Works, Penacook New Hampshire, probably in the 1930's. Model 584 AC Amp meter. Mount diameter is 2-3/4 (housing OD) and face diameter is 3-1/2 inches. Untested. If not used for testing, think about your next industrial project, rat rod car project, or office and bar decor! I have other vintage meters listed, so take a look! I will combine shipping.