Here's an interesting one. White gold plate single hinged case. No engraving on case sides.The more I looked at ads, the more complicated it got.....
It appears that in 1924, there were models 3176 (solid gold) and 3155 (green or white plate). These 2 models are advertised as 17J with "shell shaped" lugs, for lack of a better description. In 1925 the Banker appears in ads as 15J with the same shell lugs and offered in solid, green or white. Solid with 17 and plated with 15. Mid 1925, both 3155 and Banker appear in ads and the lugs change to sticks, like subject watch. It appears that by late 1925, both the 3176 and 3155 disappear, leaving the Banker with stick lugs and 15J movement for plated models. It would appear that these 2 numbered watches became the Banker, so one has to wonder if the 1925 ads for plated 3155 just re-used the initial ad text for the gold model without calling out the jewel difference.?
1924 ads for solid gold 3176 list as 17J also available in plate with no mention of plated jewel count. The earliest 1925 Banker ads list solid gold (17J) and plated with 15J. Is it possible this is a 3155 and was also a 15J watch, like the Banker it seems to have become?
Subject watch, by case s/n is either the earliest Banker yet to be ID'ed, or a transition watch from 3155 to Banker? Perhaps true 3155 case with downgraded movement jewels for the transition to Banker? The lack of case engraving has me mystified. Most ads for 1924 and 1925 for both models I was able to enlarge don't seem to show side engraving? We have no examples of 3155 in the database for comparison. This is the only watch of this style case and face I have ever encountered that was unengraved. Take note that it is interior marked "Bulova Quality" without "American Standard."
I leave this one to my esteemed fellow panel members to "split hairs" and ID. I personally can't decide at this point.