1960s Delvina Super Compressor

The term Super Compressor refers to diving watches enclosed in a special case manufactured by EPSA, which was characterized by high water resistance thanks to the case back, which, as the depth and thus the pressure increased, was pressed against the spring and seals inside the case and at the crowns.
Manufactures such as Zenith, Jaeger-Lecoultre and Longines used EPSY envelopes from the 1950s to the 1970s - Delvina is definitely one of the less known and no longer existing manufacturers, which, in my opinion, only makes it unique.
The second crown, of course, serves to operate the internal rotating ring

The watch has slight scratches and dust on the dial, the case has scratches and dents as befits a 50-year-old diver. The ETA 2783 mechanism with a quick date change, despite the unknown service history, is in good working order.