Feature:1. Smart Socket Tester: This socket tester can test every pin socket functions of the car, and the whole operation is very simple.2. Clear in Indication: There are clear lights and label on the test tool, this tester indicates quickly if a failure concerns the wiring.3. Wider Compatibility: One side can connect the 7 pins plug of a trailer and another side can connect the 7 pins socket of a car for test.4. Good ABS and Copper: Mainly made from premium ABS and copper material, not likely to malfunction and has good durability for long term use.5. Convenient Carrying: Comes with a compact size and a light weight as well, the trailer socket tester is very convenient to carry with you.Specification:Item Type: Trailer Socket TesterMaterial: ABS, copper. Battery Specification: 9V battery, not included. Applicable Range: Suitable for the test of N type 7 pin trailer plug socket connector. Trailers and RV can also be used. .Package List:1 xTrailer Socket TesterNote:The tester is not compatible with the LED light unit on the trailer.