This 4-in-1 drawing tool can be used as a compass, a ruler in inches, a ruler in centimeters and a protractor. The opening in the Direct View (TM) compass point provides the easiest, most accurate location for all circle constructions. Quick-Set (TM) radius indicator allows for immediate comparison of inches and cm. Built-in protractor measures and constructs angles. Made of SAFE-T (R) Plastic (R) for a safer, longer lasting tool. Circles can be drawn with diameters from 1'' to 9 3/8''.