Efficient Circuit Testing With a 13.5 ft cable, this test pen lets you reach across a wide range of electrical systems for accurate, easy diagnostics in automotive and other applications. Versatile Functions Identify polarity, assess motor and lamp functionality, test conductivity, and trace and locate short circuits for precise vehicle troubleshooting. Safety and Reliability Built-in short circuit protection helps prevent damage and supports fast detection of poor ground connections, delivering a dependable and secure testing process. Easy to Use To check polarity from battery to tip, connect the Voltage Tester Pen to the car’s battery and toggle the power as needed. Use Scenarios - Inspect battery, starter, and charging circuits in cars and trucks. - Verify polarity and grounding on motors and lighting circuits. - Trace shorts and test conductivity in wiring harnesses and electrical assemblies.