Pololu 1000:1 Micro Metal Gearmotor HP is a miniature, high-torque gearmotor with a 986.41:1 gearbox, making it a great choice for applications requiring fine control at very low speeds. These units have a 9.2mm (0.365") -long, 3 mm-diameter D-shaped output shaft.
Pololu 1000:1 Micro Metal Gearmotor HP has an extremely high gear ration, which makes it a great choice for applications that require extremely low motor speeds. With no load, the Pololu 1000:1 Micro Metal Gearmotor HP output shaft turns at approximately 32 RPM at 6 V, and we were able to achieve rotation rates of around 2.5 RPM at 0.5 V.
Note: Because of the high gear ratio, these motors can generate enough torque to damage themselves, so you should avoid stalling them.
Pololu 1000:1 Micro Metal Gearmotor HP is intended for use at 6 V, though in general, these kinds of motors can run at voltages above and below this nominal voltage, so they should comfortably operate in the 3 – 9 V range (rotation can start at voltages as low as 0.5 V). Lower voltages might not be practical, and higher voltages could start negatively affecting the life of the motor.
Note: stall torque and current specifications are theoretical values; stalling the motor will damage the gearbox.
Pololu website:
https://www.pololu.com/product/1595