A early Panerai (Italian made) diving compass. A few were made for the German commando frogmen called "Kampfschwimmer" who belonged to the KriegsMarine ( 1943-1945 )
The cardinal points are in German: Nord, Ost, Süd, West.
For more info see: In German
Contains Radium paint. (1.5 micro sievert/h)