Pololu 20mm Metal Geared Motors

The 20D mm line of brushed DC gearmotors all have the same dimensions except for the length of the gearbox, and they are intended for use at 6V. In general, these kinds of motors can run at voltages above and below this nominal voltage, so they should comfortably operate in the 3 – 9V range. Higher voltages could start negatively affecting the life of the motor, and lower voltages might not be practical. Four different gear ratios are available: