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, 9 ft to switch, 1 ft to battery). Ideal for ATVs, UTVs, and Autos. For marine application it is generally best to have a custom one built.