Amazon.com : Black Trike Conversion Kit for 20 inch Bicycle. Comes with Two 20 inch Hollow-Hub Steel Wheel 36 Spoke. Tricycle, Trike, Three-Wheel Bike Conversion kit : Sports & Outdoors
Amazon.com : Alta Tricycle Trike 20" Conversion Kit with Plate, Multiple Colors (Black) : Toys & Games
VINTAGE! 12-16 TRIKE CONVERSION KIT 1 SPEED COASTER 5/8 AXLE IN CHROME OR BLACK. | eBay