This hollow drafting scale is made of extruded aluminum and features a photo anodizing process that ensures the calibrations and color remain permanent. This process also provides a smooth, tick-free finish and calibrations which are resistant to cleaners and solvents. Dimensions: 1.022" wide per side and calibrated 16, (1/8, 1/4), (1/2,1), (3/8, 3/4), (3, 1-1/2) and (3/32, 3/16).