When replacing the factory radio with an aftermarket radio a special harness is required. This wire harness fits the plugs removed from the factory radio allowing you to retain the original plugs should it become necessary to re-install the original radio. Because each wire harness is custom designed to fit the plugs of a specific car manufacturers, they are not included with new replacement radios. Another good reason to use a wire harness to replace the factory radio is that the wires meets EIA (Electronic Industries Alliance) industry standard colors representing the function for each wire.