This 4-pack 12V automotive relay kit is built to handle demanding high-current switching applications with ease. Each relay is rated at 40 amps and operates on a 12-volt coil, making it well-suited for use in cars, trucks, motorcycles, boats, and vans. The 4-pin SPST (Single Pole Single Throw) design offers straightforward wiring and reliable automatic operation. Each unit comes pre-wired with a harness socket featuring heavy-duty, color-coded wires in both 12 AWG and 16 AWG gauges, simplifying installation and reducing the chance of wiring errors. Copper contacts deliver consistent conductivity and long-lasting performance under load. The compact plug-in relay body includes a screw mount bracket for secure, stable positioning in tight engine bays or electrical panels. The wiring diagram is clearly printed on each relay body for quick reference. Whether you're upgrading your vehicle's electrical system or replacing a faulty relay, this kit provides everything needed for a clean, dependable installation right out of the box.