Pololu 391:1 Metal Gearmotor 20Dx46L mm 6V

These small brushed DC gearmotors can deliver a lot of power for their size. This version has a 6V brushed DC motor combined with a 390.6:1 metal spur gearbox. The gearmotor is cylindrical with a diameter of 20 mm, and the D-shaped output shaft is 4 mm in diameter and extends 18 mm from the face plate of the gearbox. Key specs at 6 V: 37 RPM and 170 mA with no load, 260 oz-in (19 kg-cm) and 2.9 A at stall. Note: the gearbox torque limit is 70 oz-in (5 kg-cm); see detailed description for important product limitations.