This 4-pack 12V relay kit delivers reliable power distribution for a wide range of automotive and marine applications, including cars, trucks, motorcycles, boats, and vans. Each JD1912 relay is rated at 40 amps and operates at a 12-volt coil voltage, making it well-suited for handling demanding electrical loads. The 4-pin SPST design features automatic operation and a screw mount bracket for secure, stable installation wherever you need it. Each relay comes pre-wired with color-coded 12 AWG and 16 AWG wire harnesses, allowing for quick plug-and-play setup without the hassle of additional wiring work. Copper contacts ensure durable conductivity and long-lasting performance even in tough conditions. The clearly labeled pin diagram (85, 86, 30, 87) printed directly on the relay body makes wiring straightforward for both experienced installers and beginners. Whether you're upgrading your vehicle's electrical system or replacing a faulty relay, this kit provides everything you need to get the job done right.