Faber Castell 4/98/388 Electro 56 cm 22″ slide rule 1937 Germany

This is a extra long slide rule used for electrical calculations. It has not one but two cursors with different indicators (letters and harilines). It has beens made extra long to give the user more possibilities and better chance to make accurate calculations. It comes in the original very though black cardboard case that is still complete with only small has signs of storage / use. The rules is marked 37 on the back wood part so from 1937. Everything is complete, no cracks, chips or dings and in working condition with noticeable signs of use and age, mostly discoloration to the front where the insides are more white. This rule has a wooden base and a metal part on the slider end. It measures 55 cm or 22 inches wide. Check the attached video on how to work your vintage man tool : slide rule operation instructions!