To calibrate a Folai stud finder, follow these steps:
1. Press and hold the power button until the device beeps.
2. Place the stud finder flat against the wall and slowly move it horizontally.
3. When the stud finder detects a stud, it will beep and display a light.
4. Mark the location and continue scanning for additional studs.
5. Repeat the process if needed for accurate calibration.