This 7 pin trailer tester plug has one side to connect the 7-pins plug of a trailer and another side to connect the 7-pins socket of a car. This tester indicates quickly if a failure concerns the wiring of the car or the wiring of the trailer, which can effectively test what the problem is for 7 pins plug and socket connection.

7-Pin Trailer Tester Plug
Copper tester plug, this 7 pin trailer tester is corrosion and abrasion resistant, durable to use.

Ergonomics Button
Specially design with ergonomics button, comfortable to press, relieve your hands fatigue.

Display Panel
Different lignt displays the different test problems, easy to recognize and use.
link:http://www.willingcorp.com/auto-tools/trailer-socket/7-pin-tester.html