StrobeStopper increases towing safety, to help prevent Rear-End Collisions! It is designed for LED Trailer lights that anyone hauling a trailer can install effortlessly. You simply plug one end of the harness directly into the back of the tow vehicle (typically a 4-Flat or 7-Way), and the other end into the trailer. Once attached correctly, the device will make your trailer brake lights blink rapidly, then stay solid after catching the attention of the drivers behind you MUCH faster!