12mm hex hubs for the ML-30 / ML-50 motors.
There is a 6 mm hole in one side with set screw for the ML-30 or ML-50 motor shaft and an 8-32 tapped hole in the other side to retain the wheel. Wheels and tires sold separately. Sold in pairs.

ML-30 30:1 Geared Motor

ML-50 50:1 Geared Motor

F5 Wheels - grey