o Chartpak o - Adjustable Triangular Scale, 1/16", 1/8", 1/4", 1/2", 1 Adjustable triangular scale for architects with rotating dial at each end to change units. Adjusts to 1/16, 1/8, 1/4, 1/2, 1:1 and 2:1. Versatile design for architects. Change units quickly and easily by rotating dial at either end of scale. 12'' measuring length, exact calibrations. Manufactured of the highest quality aluminum.