The Vintage Wrist Watch Company has dated this piece to the 1930s.
The watch has a stem-winding movement, calibre 19-34-3-T, which is working nicely. The movement is signed with the Zenith name and the serial number 3,246,537 dates it back to 1939.

The watch measures 50mm diameter excluding the winding stem and the loop. The case is stamped as being Metal Blanc, or white metal. The back of the watch has the pheon, or military arrow, together with the code HS3 - hydrographic services (this code designates a deck watch adjusted for isochronism in a minimum of two positions), while the inside has the Zenith logo. Overall the case is in good condition, just a couple of “dings” to the back.

The acrylic lens is in good condition.
The dial is signed with the Zenith name, together with an issue number. The dial is in good condition and has blued steel hands, a subsidiary seconds dial and an outer minute track with 24 hour numbers. There is a chance that this is a later, but genuine, civilian dial.
The watch will be sent in a new presentation box.
The Vintage Wrist Watch Company has dated this piece to the 1930s.
Specialists in antique and vintage wrist watches and pocket watches
You can view the stock and full dealer information on the The Vintage Wrist Watch Company Profile Page