For an easy installation a wiring harness is a must. This harness will save you time and money during installation. Comes with 12 VDC relay, battery terminal connections, in line fuse, red illuminated rocker switch (requires a 3/4 in hole to be flush mounted) and 19 ft of wire (from the relay – 9 ft to each light (2 strands), 9 ft to switch, 1 ft to battery). Ideal for ATV’s, UTV’s, and Auto’s. For marine application it is generally best to have a custom one built. There is a water-proof connector on the end of the wire going to the light that our backlit and DR series light bars connect to. For all other lights you will need to cut off the plug and make up that connection.