Wide application:Fit 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.)Checking Short Circuit:Find intermittent circuit problems by flexing wires or connectors and listening for a change in the receiver tone Allowing you general tracing or pinpointing the problem location.Locating Open Circuit:Judge continuty of the cables or wires.Easy to use:7" flexible probe allows reaching wires in congested places.Signal reception:Receive the tone signal on the cables or wires,Send a single solid tone or a dual alternating tone to the object cables or wires.Aging fast:Greatly reduce repair time and solve problems for consumers Specifications:Power:Two 9V batteries (Not Included In Package)Material Type:coiled steelItem Type:Electrical Testers & Test LeadsPackage Size:20*20*3cmPackage Weight:388g Package List:1 x Automotive Short and Open Finder Sender1 x Automotive Short and Open Finder Receiver1*Carrying bag1*English User Manual