12" triangular scale in Staedtler's professional series is ideal for engineers. Color-coded grooves in the high-impact polystyrene plastic ensure quick and accurate selection of the desired scale. Three sides with six different scales feature die-engraved graduations. Engineer triangular scale is fully divided: 10, 20, 30, 40, 50, 60 parts to the inch. Easy-to-read printed graduations will not rub off.