The color coded center groove easily identifies scale graduations. Measurements are precision-etched into a durable laminated plastic for accuracy. Comes in a protective case. Engineering Scales—Color coded, 10; 20; 30; 40; 50; 60 parts per inch. Ruler Type: Triangular Scale; Length: 12"; Standard Scale: 10"; 20"; 30"; 40"; 50"; 60"; Material(s): Plastic.