It is covex in shape, sports a two prong plug.
The back reads: Use On A.C. Current only - 60 cycle - 115 volt-2W. M I by United Clock Corp. Brooklyn N.Y. Model 66.
Measures: 13" across frame - the clock 6 3/4".
Such a sweet piece, aside from its graceful frame shape it has such a beautiful face - elegant lettering that surround an embossed basketweave pattern in center :)