Practical function: This automotive relay tester is mainly used to test the condition of automotive relays. If the tester lights up green, the relay is normal, and if it lights up red, it is not normal. Good material: This car battery tester is made of high-quality plastic and metal materials, and has the characteristics of sturdy and practical, fine workmanship, excellent performance and durability. Easy to use: This relay tester can be configured as 4-pin and 5-pin relays, through a continuous car battery (11V-15V) to the relay coil, the tester can correctly check the contact function of the relay. Note: The car battery must be a 12V battery, the voltage should be between 11 and 15V. The resistance of the coil is preferably at least 20 ohms. Compact Design: 12 x 6 x 2.5 cm / 4.7 x 2.4 x 1.0 inches, small size and compact structure, easy to carry and use. You can test anywhere as you like. Wide Application: The relay tester observes the contact data, closing time, inertia of the