Material: The car battery tester is made of plastic and metal, sturdy and practical, well made, powerful and durable. Quick test device: adjustable to 4 and 5 relay pins, by connecting a continuous car battery (11V-15V) to the relay coil, the detector can correctly detect the relay contact function. Portable size: 11 x 5.7 x 2.5cm, small size, compact structure, easy to carry and use. You can test it anywhere. Function: Designed to test the status of automotive relays. The green light of the tester indicates that the relay is normal, and the red light indicates that the relay is abnormal. Wide range of applications: The tester observes contact data, closing time, relay inertia, etc. in each test phase. Quick and easy testing of automotive relays provides a convenient and intuitive diagnostic method.