The Sterling Loose Leaf Binder Protractor Set with Slide Rule #587 is a vintage collectible item perfect for engineering and science enthusiasts. This set includes a protractor set with a slide rule, making it a practical and versatile tool for various calculations. Ideal for those interested in retro technology and historical mathematical tools, this item offers a unique blend of functionality and nostalgia for collectors and hobbyists alike. The slide rule, compass, and ruler are all marked Sterling. Detailed Conversion Table on back.