This HID relay wiring harness is an important component in HID lighting system. The HID Battery Relay Harness is used to connect the HID Conversion Kit directly to the car battery and is suggested for vehicle that does not provide enough startup power for the HID Kit. The Battery Relay Harness will draw power directly from your vehicle battery instead of your factory wiring. Which is more safe for your vehicle and helps protect your factory wiring and also extend the life of the hid ballast. The harness connects to the factory OEM socket and does not require any cutting or splicing, using the OEM connections will allow you to turn on and off your headlight using your factory light switch.