VERSATILE AUTOMOTIVE RELAY TESTER: This DC 12V automotive relay tester is designed for quick and accurate testing of both 4PIN and 5PIN relays, making it an essential diagnostic tool for mechanics and car owners. Compact and USB rechargeable, it ensures reliable performance and convenience for a wide range of automotive applications. USB RECHARGEABLE & PORTABLE DESIGN: Featuring a built-in rechargeable battery powered by a 5V DC, 1A-2A USB input, this relay tester eliminates the need for single use batteries. Its lightweight, portable design allows users to test relays anywhere, offering flexibility and efficiency during vehicle maintenance or roadside troubleshooting. INTELLIGENT LIGHT INDICATOR SYSTEM: Equipped with clear LED indicators, this tester simplifies diagnosis, the green light flashing ten times signals a fully functional relay, while a red light instantly alerts users to malfunctions. BUILT-IN SIDE LIGHT FOR ILLUMINATION: For added convenience, a side light is included to illuminate dark or hard-to-see areas during testing. This practical feature enhances visibility under vehicle dashboards or engine compartments, allowing safer, more precise relay inspection even in low-light workshop or roadside conditions. UNIVERSAL COMPATIBILITY: Designed to handle most DC 12V automotive relays, this universal tester supports diverse vehicle types and relay configurations. From cars and trucks to motorcycles, it provides consistent testing performance, helping you identify faulty relays within seconds and ensuring reliable operation of automotive electrical systems.