Tower Pro SG90 it is an ideal servo motor for your small mechanisms. It is fully compatible with Futaba remote controls and you can use it in your RC vehicles. In addition, you can easily use it in your own robot projects with the PWM signal you can receive from many microcontrollers.
The gearbox is plastic. It is shipped with servo horns and other parts. As with other hobby servos, the gears can be broken by turning the motor shaft left and right by hand, such manual intervention in the motor should be avoided.