The Triplett Model PR600 Non-Contact Phase Rotation Tester determines the correct phase wiring sequence for 3-phase system installations. You can clip on to insulated wires with a maximum conductor diameter of 1.3'' (33mm). View the results on an easy-to-read LED display to see phase direction (clockwise/counterclockwise) and which phases are live. A buzzer sounds to indicate live wire and clockwise (intermittent beep) or counter clockwise (continuous beep) direction. There are 2 selectable brightness levels for use in sunlight or dimly lit areas and a back cover magnet that mounts on to metal surfaces for hands-free operation. Additional features include Auto power off and Low Battery indicator. CAT IV 600V safety category. Includes 59'' (1.5m) test leads with large color-coded alligator clips, 9V battery and soft case.