Still don't know if I'll keep it or not, as I have some other projects, and especially an US NAVY....
1952???
Well...The FF were protos in 1952 if I'm not wrong, and they were released in 1953.
So, if it is a FF, it is a proto.
Not a Sub, as they were born in the same era.
Diving watch or other?
Damn, I will spend all the night to find...
Best,
Nicolas