This simple device can be used to operate or test servo motors. There are 3 modes to check servos;

1. Manual mode: turn the knob
2. Neutral mode: make the servo go back to the neutral point
3. Automatic: window wiper mode: make the servo swing like a window wiper in the biggest angle. Push button to change between modes. Lights indicate mode.

You can connect 1-3 servos simultaneously. It can also be used to check the operation of any servo motor whether fitted or not.