I have this orphaned case. The back is marked Waterproof to 666 Feet. Self winding. Antimagnetic. Stainless Steel Case.
The unusual thing is, as can be seen on the photo, is that the case appears to be mono block style. In that the case back does not remove.
The interior of the case back is marked as follows:
11H 9206 11HC
All of the markings seem to be Bulova marks (I assume).
The case design would suggest it is mid/late 1960s to early 1970s.
Any Ideas ?