Unknown German signal

This insulator appeared to be just another No Name petticoat rest until I began cleaning it for photographing.  That was when I discovered the words "MADE IN GERMANY" ink stamped inside the insulator, at the top of the pinhole.  I have contacted numerous American and European collectors and all indications to date are that this appears to be the only known pintype marked in this fashion. The actual manufacturer is yet unknown.

Characteristics: Color(s) --- white Pinhole(s) --- not glazed Pinhole Top(s) --- flat Fire Rested --- petticoat Wet/Dry Processed --- wet Marking(s) --- ink stamped on pinhole top (inside the insulator) "MADE IN GERMANY" in between concentric circles