Keuffel Esser 4181-3 Duplex DeciTrig slide rule case 1960 USA

This is a quality build pocket slide rule with elaborate calculation options through 21 different scales. This great rule also come in the original signed dark green leather case (some scuffs where the brown shows through the green top layer). This K+E rule is in good condition, with only signs of normal use and age. It is made entirely of Ivoride plastic with metal ends and partial metal cursor. This full size 4181-3 model Duplex Decitrig measures ca. 32 cm or 13 inches wide. Check the attached video on how to work your vintage man tool : slide rule operation instructions!