Staedtler(R) Engineers Printed Scale, 2 Packs 12" triangular scales are ideal for engineers and engineering students. Easy-to-read, printed graduations will not rub off. Engineer triangular scales are fully divided: 10, 20, 30, 40, 50, 60 parts to the inch. Scales are made of high-impact polystyrene plastic. Three sides with six different scales feature die-engraved graduations.