For closed loop speed or position control applications like inverted pendulums, autonomous mobile robots, DC servo motors, conveyor belts, and more, the 25GA 12V 125 RPM DC Motor with Encoder and Gearbox is perfect. The DC motor, gearbox, and quadrature encoder make up the device's three main components. The nominal voltage at which the DC motor runs is 12V. The purpose of the metal gearbox is to increase the output torque while decreasing the input speed. Metal is used to make the gearbox and motor for strength and durability. The encoder uses two Hall effect sensors to function as a speed and direction sensor. The DC motor operates between 5 and 12 volts, and the applied voltage affects the output torque and speed.