Model: SP5-1022
Rear Wheel Freewheel Mechanism - 16 Tooth,not used as a chain sprocket,attached to the larger chain drive sprocket to allow the rear tire & wheel assembly to spin in reverse .
Works with 2-1/8" ID chain sprockets with 4 bolt mounting pattern. Fits 1-3/8" OD electric scooter and bike threaded wheel hubs, and has 16 teeth