Wichmann electrical slide rule with side wheels

Data:

• Electrical slide rule, distributed by Wichmann Berlin.
• There is no model name, no number, no maker, neither on the black paper box.
• It has two metal wheels on each side and sort of metal rails in the slide. By using your thumbs you can move the slide. Two screws are missing, but it works. I think this construction was not very successful, because I cannot find this model in the online collections.

Questions:

1. Who built this slide rule?
   Maybe KHH? Hans Kordetzky
   David Rance assigns a similar Electro slide rule, without the wheels, to KHH. sliderule@groups.io See also Wer Waren Koch-Huxhold-Hannemann
    
2. When ?
   The Wichmann-Katalog 1910/1912 already shows a slide rule with “Mikrometer­einstellung” but in the 1939 Wichmann catalog no such slide rules are shown. Hans Kordetzky
    
3. Are there other examples ?
   Hans Kordetzky's RST presentation shows various Wichmann slide rules with “Mikrometer­einstellung” Andries de Man