DescriptionK&E K-12 Prep Slide Rule, 68 1892. Made by Keuffel & Esser Co., no date, circa 1962-1972. 10" all plastic (white Vinylite) slide rule except for metal spring in otherwise all-plastic indicator. Lacking: original case (plastic vinyl sleeve) or instructions. All markings are in a dark green ink matching the plastic bracket ends. K&E general offices and factories were in Hoboken up to December 1968 and after that in Morristown, N.J. Actually made in Connecticut by K&E Salisbury Products Division. Item is only marked with "Keuffel & Esser Co.", "K&E" and "Made in U.S.A." plus the rule name and stock number. Rule was introduced in 1962 and production ended in 1972. All scales are on the front of the rule; reverse is blank.