This 5 Pack of 4-Pin 40/30 AMP 12V DC Automotive Relays is designed for reliable performance in demanding electrical systems. Each relay features a heavy duty construction with 12 AWG tinned copper wires, providing excellent conductivity and corrosion resistance for long term durability in automotive, marine, and off road applications. The waterproof design helps protect the relay from moisture, dust, and debris, ensuring consistent operation even in harsh environments. With a 40 amp continuous and 30 amp resistive load rating, these relays are suitable for controlling a wide range of high current devices such as headlights, horns, cooling fans, fuel pumps, fog lights, and power accessories. The SPDT contact type allows for both normally open and normally closed switching configurations, offering flexibility in your wiring setup. Each relay operates on a 12 volt DC coil with an 80 ohm coil resistance and a low 1.8 watt power consumption, making them energy efficient while delivering strong switching performance. The included harness features quick connect terminals for easy installation, allowing you to integrate the relay into your existing wiring without soldering. The socket mount design simplifies replacement and maintenance. Whether you are upgrading your vehicle electrical system, repairing a trailer connection, or building a custom lighting project, this relay set provides a dependable solution. Each relay is built with copper contacts for reliable current transfer and a minimum switching voltage of 6 volts DC, ensuring compatibility with most standard 12V systems. This pack gives you five complete relay and harness sets, making it a convenient option for multiple installations or replacements.