Specification: Battery : 9V Battery(not included) Voltage 12V Description 1.7 Pin Car Towing Light Tester :Test your car's towing lights with ease using this 7-pin tester. 2.Trailer Plug Socket Diagnostic Tool :Diagnose trailer wiring issues quickly and easily with this diagnostic tool. 3. Mechanical Tester :This mechanical tester is perfect for diagnosing mechanical issues in your car or trailer. Feature: 100% new and high quality. Good construction, high-and low-temperature resistant, acid and alkali resistant Compact hand held design, portable, easy to carry Just plug the tester in the 7 pin socket or the 7 pin plug of the trailer and press the yellow button on the side of the tester. Designed to indicate a failure in the wiring on both towing vehicles and trailers etc Package Included: 1 x car mountPlug Socket Diagnostic Tools