A vintage wrist worn divers compass dating to the 70's/80's in wooden box. As worn by the SBS, SAS and Clearance divers of the time. Box measures 12cm x 10cm x 7cm. Compass diameter 5cm.
I did a few miles with one of these style, very good to read in the murk.
We generally had them on a swim board with a depth gauge and watch. The depth  gauge was to not exceed the safe limit on O2 but any gas mix.