Together with the motor, the gearbox is an essential component for powering a robotic or mechanical project. This kit consists of a gearbox with a single Type 130 motor and can be conveniently assembled one of four different gear ratios: 12.7:1, 38:1, 115:1, or 344:1.. Choose the one which matches your needs. The gearbox case, gears, and crank arm are made from durable plastic material while the shaft is made from metal.