Nilight 4-Way Trailer Wiring Harness Kit 56407 Vehicle Side Custom JL Trailer Towing Wire Harness Compatible with Wrangler JL 2018-2023 and Gladiator 2020-2023, 2 Years Warranty. This 4-pin trailer wiring harness is used to connect trailer tail lights, turn signals, and brake lights. The 4-pin connector is compatible with a variety of trailers, adding versatile towing options to your vehicle. The plug and converter are made of high-strength ABS plastic, brass, and tin-plated terminals, which have excellent conductivity and are very durable.