Secure your device in a horizontal or vertical position. Wait until the angle is fixed. Then tap "0 DEGREE CALIBRATION" button gently.
In the same position, turn your device 180 degrees in the horizontal position. (Note that it is in the same parallel as the first position.) Wait until the angle is fixed. Then tap "180 DEGREE CALIBRATION" button gently.
In this case, tap the 'CALIBRATION' button. Keep the angle on the screen in mind.
If you turn the device to its initial position and the text on the screen is negative in your mind, the calibration was successful. If the results are contradictory, repeat the process.
Whether you are a universal absolute measurement, (water balance). You can find the angle difference between two surfaces using the incremental (angle meter) system.
When you use it as a water balance, open this button when you need to get an audio signal to balance your machine.