Few days ago I got as a present one very old bike frame which was almost completely stripped of paint few years ago and slight rust got on it on the surface. Only fork was in it’s original color, it was black with white or maybe golden pinstripes, headtube has some strange screw alike thing on right side.
Previous owner told me this,
Bike is from Germany, possible 1938. year, made by Mars brand. It has serial number stamped on seattube and it’s 675931
Here are few photos