DescriptionIvorite slide rule, 4181-1C, with holder manufactured by Keuffel & Esser Company, Hoboken, ca. 1953. Engraved white plastic with aluminum fittings and clear plastic slide, 7" wide x 1-5/8" high. With: dark green leather sheath with pocket clip; original two-piece tray box with end label; softcover 123-page manual, last copyright 1947, ca. 5" x 7" high; 8-page supplement to the manuals copyright 1953, ca. 5" x 7" high; instruction sheet laid-in box. All items were originally stored in the box. Object name as found on box label: [Catalog no.] 4181-1C | Ivorite Slide Rule | With Scale Arrangement as on the | Log Log Duplex Decitrig.