Heavy Duty Tester Signals With A Light And Buzzer. The tester kit tests low voltage up to 28 volts. Also finds electrical shorts, checks polarity, detects battery drain, and checks circuits from a distance. Heavy-duty coil cord extends over 8 feet. Detachable, spring-loaded hook pulls the center of the wire into the probe every time. Attach alligator clip to the probe when a clip-on connection is needed.