A Relay Harness connects the HID Conversion Kit directly to your cars battery. The Relay Harness will draw power directly from your vehicles 12 volt battery instead of your factory wiring. This will elimates issues caused by vehicles with DRL (Daytime Running Lights). Relay Harness also protects your factory wiring and extends the life of the hid ballast. The harness connects to the vehicles 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. One Relay Harness is needed for each HID Kit.