Tricycle Trike Conversion Kit for 7 speed Use Hollow Hub 15mm axle Black | eBay
Traditional Tricycle Conversion Kit w/ Li-Ion Battery | E-TrikeKit™
Amazon.com : Lowrider Chrome Trike Conversion Kit for 26 inch Bicycle. Comes with Two 26 inch Hollow-Hub Steel Wheel 72 Spoke. Tricycle, Trike, Three-Wheel Bike Conversion kit : Sports & Outdoors