This is a zero size, 7 jewel movement, Elgin grade 173. The odd thing is that it has been mounted in what seems to be, outwardly at least, as 12 size case. As a result it has no second hand. It has a metal factory dial, marked Elgin, with no sub-dial, no seconds marks and no hole for where a second hand would be, if this were a 12 size movement.
This watch movement was made about 1897, however the style of the case and dial indicate the late 1920s, or early 1930s. The inside back is marked "RADIO", and 14 kt gold filled, 20 years.