LUFKIN PLUMBER'S RULE

This rule is used when working with 45°elbows and it eliminates figuring and chance of error. It is graduated on one side, in black, consecutive inches to 16ths, both edges. Other side in, 45°scale inches to 16ths, upper edge only. Turning rule from black to red gives, at a direct reading, the corresponding 45°elbow measurement.