1.Automotive Short and Open Finder: Is designed to identify and trace wires or cables without damaging the insulation. You can also use it in checking for short circuit and locating open circuit and so on. Included in the set are Sender and a Receiver with a flexible thus, tracing wires made possible even inside bundles, conduits, behind panels, under carpets, upholstery, etc 2.Locating Open Circuit: Open Wire Detector, powered by 2pcs9V Batteries. It detects and alerts you immediately where a circuit is open. You can quickly and easily Locate short circuits, open connections, broken wires, current leaks and even trace wires. Transmitter and receiver LEDs show open or short circuit conditions 3.Checking Short Circuit: Short Circuit Finder Automotive,you can also find intermittent circuit problems by flexing wires or connectors and listening for a change in the receiver tone, 7 inch Flexible Probe Help Reaching Wires in Congested Places 4.Suitable For DC 6~42 Volt Circuit Power: Electrical Circuit Tracer will work on all kinds of circuits with voltages between 6 and 42 volt DC. (such as those found in automobiles,trucks,tractors,boats,RVs,etc...With its wide working voltage range)