A small, low-power motor with a 5:1 metal gear, 6 V operating voltage, 0.02 A to 0.36 A power consumption, 2500 RPM speed and a maximum torque of 0.05 kg * cm. Pololu 1100

10:1 Micro Metal Gearmotor HP

10:1 Micro Metal Gearmotor HP with Extended Motor Shaft

10:1 Micro Metal Gearmotor

30:1 Micro Metal Gearmotor HP

30:1 Micro Metal Gearmotor HP with Extended Motor Shaft

30:1 Micro Metal Gearmotor

30:1 Micro Metal Gearmotor with Extended Motor Shaft

50:1 Micro Metal Gearmotor HP

50:1 Micro Metal Gearmotor HP with Extended Motor Shaft

50:1 Micro Metal Gearmotor

50:1 Micro Metal Gearmotor with Extended Motor Shaft