Amazon.com: Oyviny 4-Way Flat to 7-Way Round Blade and 4 Way Trailer Wiring Harness Adapter Vehicle-Side 4 Pin to Trailer-Side 7 Pin and 4 Pin Dual-Output Connector with Mounting Bracket for Truck
Reese Adapter 7 Way Round to 4 Way Flat in the Trailer Parts & Accessories department at Lowes.com
Seven-Way Blade to 4-Way Flat Trailer Adapter
Pico 6573PT 7-Way RV Blade Male to Both 6-Way Round and 4-Way Flat Female Trailer Connector Adapter
Hopkins Towing Solution 4 Flat to 7 Blade Adapter
Amazon.com: Hopkins Towing Solutions 47185 Multi-Tow 4 Flat to 7 Blade and 4 Flat Adapter : Automotive