VTG K&E Kueffel & Esser Slide Rule N4080-3 Log Log Duplex Trig Case USA 1947. This slide rule is unique as it was used or given out at the Boeing School of Aeronautics and has the person’s name on it and looks like they had it signed of where they used it or took it to? In nice condition will show pictures of the leather case. Shipped standard shipping. Feel free to ask any questions or more pictures.