Alvin 306A architects scale is constructed of durable, high-quality, solid aluminum. Printed calibrations on a durable, ultra-smooth surface that resists stains and abrasions. Color-coded furrows for quick and easy reference. 6" triangular scale with standard architectural graduations of 3/32, 3/16, 1/8, 1/4, 1/2, 1, 3/8, 3/4, 1 1/2, 3" to the foot; one edge in 16ths. Compact size is great for travel and on-the-job field use.