Micro DC motor FF-180 motor reference parameters: Use voltage: 1-4.5V Number of revolutions: 4500 revolutions (2.4V) or around 9000 revolutions (3.7V) Current: 0.27A (3.7V) Motor case size: Diameter: 19.86MM Thickness: 15.32MM Chassis length: 31.94MM Output length: 25.22MM (length from step to runner. Step: 1MM, diameter of output shaft on the wheel: 2.5MM) Wheel diameter: 9.5MM Total wheel length: 18MM Wheel bottom diameter: 6MM Screw center distance: 12.35MM