"kmk. a" headphone/microphone??

[Admiraal]

I resently found this in Normandie at the position of Pz Gr Reg. 156. from the 116. Pz Div.
It are parts of some sort of telephone/headphone/microphone thing but i have no idea, pictures:




On one of the parts i see "43" stamped in red, that must be the date.
Also on it is: "kmk. a", "9652" and 3 circle bakelite stamps.

As extra info; with it i found some radio parts and a lock, total shot of it:

[Admiraal]

Could those rusted radio parts as seen in the last picture of my first post be "EF13" parts? as seen on this page (if you scroll down a bit).