Nestler 43 System Hoffmann Concrete slide rule in box 1930 Germany

This interesting slide rule was made by the German company Nestler. This is the model 43 made for calculating concrete constructions. It comes in the original black cardboard box, signed with Nestler and the slide rule number 43 (also on side). It measures ca. 29 cm or 11 1/2 inches long. The slide rule is made of mahogany wood, the slider is made of glass and metal. All parts are complete and it is in working order. The middle part can be reversed for more calculations (reverse 1400kg is shown in the pictures, hence the small color difference, the front 1200kg matches the color of the front rule parts. It has some signs of age and use but not a lot, no chips, back is good as well. The inside of the box has some tears. Check the attached video on how to work your vintage man tool : slide rule operation instructions!