This interesting slide rule that was made by the German company Nestler. This is the model 33 made for calculating chemical reactions. It comes in the original cardboard signed holder. It measures ca. 29 cm or 11 1/2 inches long. The slide rule is made of wood, the slider is made of glass and metal. All parts are complete and it is in working order. It has signs of age and use but not a lot. Check the attached video on how to work your vintage man tool : slide rule operation instructions!