The REESE Towpower Professional Wiring Adapter is a heavy-duty vehicle-to-trailer device that adapts any popular vehicle wiring system to your trailer by converting an OEM 7-way blade connector to a standard 4- or 5-way flat connector. Boasting a built-in tester that instantly checks electrical circuit for connectivity, this device displays the status using high-visibility red LEDs so you can adapt the trailer to vehicle quickly and confirm the connections are correct. This durable adapter is built with corrosion-resistant terminals and tin-plated contacts for an extra long life. When the device is not in use towing a trailer, an attached dust-cover helps keep the terminals clean and protected.