Product Introduction: Durable Material: The car battery tester is made of plastic and metal, solid and practical, fine workmanship and good performance, durable for a long time. Provides a convenient and intuitive way to diagnose, saving time and being economical. Uses 12V Power Supply: The car battery must be a 12V battery and the battery voltage is between 11V and 15V. Ideal for higher coil resistance at 20 ohms. Test to accurately check the opening and closing of the relay. Easy to Use: Small size and compact structure, easy to carry and use. You can test wherever you want. If the relay is abnormal, the red LED will light up, it is normal for the green LED to light up, relay inertia at each test step, etc. Quick and easy car relay test provides a convenient and intuitive way to diagnose. This tester is designed to test the condition of your car's relay. Description: This is a quick test tool for testing car relays, with which you can know the status of car relays. Through the continuous car battery (11V-15V) to the relay solenoid, the detector can correctly check the relay contact function. The detector observes contact data, closing time, relay inertia at each test step and so on. If all tests pass, the green light will illuminate, and if the tests fail, the red light will illuminate. Size: approx 4.724 x 2.362 x 0.984 inches. Note: The car battery should be 12V battery, the voltage should be between 11-15V. The coil resistance is preferably at least 20 ohms. 1 X Relay Tester