The TowSmart ProClass 7-Blade to 4-Wire Flat Trailer Light Wiring Adapter with Wire Tester and Ergo Grip is the quickest and easiest way to make electrical connections when hauling a trailer that has a different wiring configuration than the tow vehicle. This adapter is ideal for tow vehicles equipped with a 7-blade connector to be able to tow a trailer equipped with a 4-wire flat connection. Built-in troubleshooting, the LEDs illuminate when stop, turn signals, or taillights are activated. The single housing design plugs into your vehicle's electrical socket and requires no wiring. It provides an ergonomic, durable plastic construction that is corrosion-resistant to withstand extreme weather. LED test lights verify wiring electrical continuity Provides electrical tow functions for brake, turn signals, taillights, and ground Dust cover provides connector protection from the elements