Heavy Duty Car Trailer 12V 7-Pin Plug Socket Wiring Circuit Tester Universal Auto Towing Lights cable Testing Tool Feature: Portable, easy to store and hand held design. Durable black plastic cotruction. This 7 Pin Tester is designed to indicate a failure in the wiring on both towing vehicles and trailer/caravan, etc. You just plug the tester in the 7 pin socket or the 7 pin plug of the trailer or caravan and pre the yellow button on the side of the tester. With a 6 LED light system. All the LEDs light up when the wiring is good. Makes the checking of the wiring quick, easy and very simple. Specification: Product Size: about 20 x 6 x 4 cm/7.9 x 2.4 x 1.6" Voltage: 12V Material: ABS Copper Color: Black Package included: 1 x Wiring Circuit Tester ( 9V battery is not included ) Notes: Conversion1 inch = 25.4mm or 1mm = 0.0393 inch 1. Due to the difference between different monitors, the pictures may not reflect the actual color of the item. 2. Compare the detail sizes with yours, please allow 1-3cm error, due to manual measurement. 3. Please leave a meage before you give the bad feedback, if the products have some problems. Thanks for your understanding and have a nice day!