And that's only half of it. There is an umbilical battery pack.
Search TBLAP for "Automatischer Zielscheinwerfer fur Mehrladepistolen"
Also several threads on this on this forum.
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It might be amusing to make a modern adaptation of this. A laser light housed in a copy of the German 'flashlight', or an actual flashlight [mini-maglight?] with wires going to the grip. House a battery where the Germans have the bulb [vertical housing] and the bulb in the under-barrel housing. Copper/bronze grip panels. You might have to spit in your palm before using it...