In the development of devices that use Micromotors or compact motors, “gearheads” are widely used to achieve the required rotational speed and torque. Also known as reduction gears, gearheads are gear mechanisms that connect to the motor’s output shaft to reduce rotational speed while increasing torque. In this article, we provide a detailed explanation—from the basics of gearheads to practical selection criteria—for engineers struggling with gearhead selection.