The finished trailer wiring harness is a complete, pre-prepared wire harness for connecting the trailer lighting to the towing vehicle. Its main characteristic is that one end is factory-pressed with a plug, usually 7-pole or 13-pole, which plugs into the car's socket. This eliminates the complicated wiring of the individual wires to the correct contacts in the plug. From the main cable, the individual colour-coded wires then lead to the rear lights of the truck, where they connect to the directional, brake and marker lights. Some kits are equipped with so-called "bayonet connectors". These are quick connectors that allow the wiring to be easily and quickly plugged directly into the tail lights without soldering or screwing individual wires together. This solution is used when building a new trailer or completely replacing old and non-functioning wiring.