Large well know slide rule that was made in Germany by A.W. Faber & Castell and is called the Castell Novo Duplex 2/83N. This is a set with box and extra answer sheet. Particularly interesting is the stamped sales person card with date in 1972. Both slide rule and slider are in good condition (some yellowing between the lines), the box is complete working condition but with a crack. It measures ca. 38 cm or 15 inches long. The slide rule and the inner piece are made of plastic. The rule is reinforced with metal pieces on the ends. Check the attached video on how to work your vintage man tool : slide rule operation instructions!