As far as I have been able to determine, this Patin master compass was fitted to Luftwaffe aircraft such as the Messerschmitt Bf 109 fighter and Messerschmitt Bf 110, Junkers Ju 88, and Heinkel He 111 bombers. As such, this type of compass would have been used in aircraft that flew in the Battle of Britain against fighters such as the Supermarine Spitfire and Hawker Hurricane. On top of the compass are the words "A-Einstellung" and "Flugrichtung" with a scale going to +/- 10. There have to be two plates. One reads: "MutterkompaB. Bauart. Patin. PFK-m. Gerat Nr. 127-110 A-2. Werk Nr. 26174. Anforderz. Fl 23331. Hersteller. PATIN." A second platereads, (which we have, you can see photos): "Achtung. Nur Stecker mit eisenfreien Kontaktplatten Fl 23332-2 verwenden." The compass is grate condition.