The Staedtler Architectural Triangular Scale STD9871831BK is a 12" triangular scale designed for professional architects. Made from high-impact polystyrene plastic, it features color-coded grooves for quick and accurate selection of the desired scale. This scale has three sides with six different scales, including die-engraved graduations for precision. Measurements are fully divided in inches to 16ths, ensuring easy readability with printed graduations that will not rub off.