Nice piece of Pilot navigator equipment from the 1980’s. The Airtour Pooleys CRP-1 Computer comes with sleeve and with manual. According to the Martinair sticker this was indeed used to navigate on a commercial airline. Some signs of use and age but in overall good condition. Pooley’s circular slide rule was produced in England. It measures ca. 21 cm or 8 inches high. Check the attached video on how to work your vintage man tool : slide rule operation instructions!