The Vintage Acu-Math No 150 Slide Rule is a rare and collectible item for enthusiasts of slide rules and engineering history. This 12" rule comes with its original case and instructions, making it a complete set for those interested in the precision and accuracy of manual mathematical tools. Perfect for collectors or those looking to add a classic touch to their engineering or math-related workspace.#item is oiled to function-feels greasy to touch but very clean .