How old is my first Zentra Tank Watch?

Hello dear watch community

I finally found my first vintage tank watch today. But now I have a problem to determine the age, the movement is a Zentra 04 which was apparently built from 1928-1945. All other Zentra movements only say "Zentra 4" and not "Zentra 04" and I'm a bit confused. The manufacturer of the watch is also a mystery to me. Roman numerals are carved into the case and lid, which may have a meaning.
I hope someone can help me with the year of manufacture.

Thank you and have a great start in 2023

·

If you could stomach an educated guess from a vintage-head, judging by similar options available on the vintage market, it’s likely to be 1930s. Without any papers or other provenance it will be difficult to date the watch exactly.

·

Also - Boden Edelstahl case, so it’ll be a German-Swiss brand.

Herman Friedrich Bauer

·
Porthole

Also - Boden Edelstahl case, so it’ll be a German-Swiss brand.

Herman Friedrich Bauer

Thank you very much for this information, I'm already desperate because I didn't find anything. I would never have thought of "Hermann Friedrich Bauer". I can hardly find any watches from the brand, although HFB is said to have had many employees.

·
Hustle4Future

Thank you very much for this information, I'm already desperate because I didn't find anything. I would never have thought of "Hermann Friedrich Bauer". I can hardly find any watches from the brand, although HFB is said to have had many employees.

HFB are the case maker. Brand is harder as the dial is sterile, but Zentra also made watches so more than likely it’s a Zentra.

·
Porthole

HFB are the case maker. Brand is harder as the dial is sterile, but Zentra also made watches so more than likely it’s a Zentra.

I can live with HFB as the case manufacturer and a Zentra movement ✌️✅