It is commonly made of plastic or aluminum, and is just over 12 inches (305 mm) long, but with only 12 inches of markings, leaving the ends unmarked so that the first and last measuring ticks do not wear off. It is used in making engineering drawings, commonly called blueprints, blue lines or plans in a specific scale. For example, "one-tenth size" would appear on a drawing to indicate a part larger than the drawing on the paper itself.