The company Klemm from Munich manufactured the Standard 10 and Standard 20 remote controls for Graupner from 1954. The identical controllers were also marketed under the company’s own name. The brochure from 1961 shows the transmitter with the order number 108, which is absolutely identical to the Graupner Standard 20 transmitter.
The Klemm company also sold its systems from other manufacturers. I have also seen a “Standard 20” with a robbe sticker. Engel had the 1- and 2-channel systems in its product range under the name Alphamat. A special feature was that the anode and heater batteries could be inserted into the receiver housing. Only the working batteries for the servo were clamped into an external battery box. The receiver had both a tube (DL 96) and a transistor (TF 65 or OC 72/76). Engel recommended the Engel Combo as the rudder machine.
Unfortunately, I have no further information about the Klemm company.