The crown is not original and the caseback possibly not original without seeing inside. Here is your watch from about 1940-45? The French factory in Besançon had their own serial numbers which were 6 digits unlike the Swiss which are 7. I’ve seen many different case backs so I assume they just used local manufacturers. Also, the factory was occupied by the Germans during the war and so I’m sure certain pieces were hard to come by on a regular basis necessitating the need for local suppliers.
Pay attention to Stötsäker in Swedish. This was probably the Swedish version. I saw an identical watch on the Swedish watch forum "Klocksnack", so it cannot be a foldable watch. Even the crowns are the same.
I am pasting a borrowed photo from this website
Hello to all Zenith aficionados on here, my apologies for posting this watch in such poor condition. I fell in love with it and brought it home but now I have my doubts if it is even genuine. At the beginning of this thread somebody mentioned that the French had their own serial number system, this may explain why I can't get a match anywhere (It was purchased in Central France). I know the strap is not original but I have my doubts about the crown and the case back. Is this poor thing worth saving or have I got myself a Frankenstein watch?
Do you have a picture of the inside caseback?