Amazon.com: OPT7 7 Pin to 4 Pin Trailer Adapter with Secure Tab, 7 Way Blade to 4 Way Flat Trailer Light Adapter, Connecter for Trailer Tow Hitch and Redline LED Tailgate Light Bar : Automotive
Curt Trailer Connector Adapter with Backup Alarm - 4-Way to 7-Way RV and 4-Way Flat CURT Trailer Wiring C57102
How to convert a 4 way flat trailer plug to a 7 way round trailer plug. Trailer Wire repair. - YouTube
Nite-Glow™ 7-Pin to 4-Pin Trailer Light Adapter | West Marine
Trailer Wiring Adapter: 7 Way Euro Round To Flat 4 Conversion Plug