High quality Pocket slide rule by the German company Aristo. This is the model 89 from the 1970’s. It comes as a complete set in the original leather signed sleeve with box, manual and package control slip. It measures ca. 6 cm or 6 1/4 inches long. The slide rule and the slider are made of plastic, manual is in Dutch. Everything is in very good condition with hardly any signs of use and age. Check the attached video on how to work your vintage man tool : slide rule operation instructions!