Extremely rare Kriegsmarine M4 Enigma patch cable

Extremely rare original Kriegsmarine M4 enigma patch cable. These cables differ from the army/luftwaffe M3 model in that the pins are significantly longer (19 mm) with the result that the patch cables of the M4 and M3 Enigmas are not interchangeable. The patch cable was used to switch letters using the "Steckerbrett" patch board of the M4 enigma machine.