DescriptionSlide rule, 5" pocket, Mannheim type, model 4150-1 made by Keuffel & Esser Co., no date, circa late 1940s to 1960. White plastic (Ivorite) with black ruling; plastic cursor with metal frame; green leather sheath with K+E logo blind stamped near open end. Serial no. 005091. Scales: DF, [ CF, CI, C, ] D, L ; blank on reversible slide; improved plastic cursor indicator. K+E factory was in Hoboken during the estimated period of when it was made. To be researched for more precise date of issue.