Faber-Castell 67/91 Pocket Slide Rule

Up for sale is a classic mid-century Faber-Castell 67/91 pocket slide rule, precision-manufactured in Germany. Highly compact and portable, this Rietz-system pocket rule is a wonderful collectible piece of vintage engineering and mathematical history. What’s Included: Faber-Castell 67/91 Pocket Slide Rule with clear cursor/runner Original dark green textured protective slip pouch (marked Faber-Castell 67/91 Made in Germany) Original two-piece cardboard box with scale diagram Original Castell Precision Pocket Slide Rules fold-out instruction guide Condition Notes: Slide Rule: In excellent vintage condition. Scales, numbers, and graduation marks are crisp, clean, and legible. The slide glides smoothly, and the cursor window is clear with intact hairline. Slip Case: Very clean with crisp gold embossing, no seam tears, and pliable material. Box: Intact with solid corners and light shelf/edge wear consistent with age. Manual: Intact and legible; has period pencil/pen hand-written calculation notes on one panel from previous owner/engineer use, adding authentic historical character.