The Staedtler Engineering Triangular Scale STD9871934BK is a 12" triangular scale designed for engineers and engineering students. It features three sides with six different scales, all with die-engraved graduations for durability. The easy-to-read printed graduations will not rub off, ensuring long-lasting use. This scale is fully divided into 10, 20, 30, 40, 50, and 60 parts to the inch, and is made of high-impact polystyrene plastic.