Gruen made attempts to sell lower grade pocket watches with the Watch Specialties, Premo, Gruen Guilds. Actually had Aeby of Madretsch make a few or at least one. Only Madretsch marked Gruen not using the Grossmann poised pallet escapement I have noticed. 1915-18 according to serial number. Lower grade but still a fine adjusted one. Has best enamel dial I have seen on a Gruen. Nice double back g.f. Gruen case oddly marked. Also shown my double pentagon Wadsworth cased Gruen Guild which is uncommonly 19j adjusted. A little newer. Unmarked serial number typical for the several lower grade models.