Stud Finder - looks for magnetic field (compass) disruptions caused by screws.
Stud finder that monitors disruptions in compass readings to identify screws in the studs in a wall. Try for lowest number possible in calibration for best results.
This uses advanced analysis of the compass hardware readings in your device for a job it was never designed intended to do. In some situations, it may work, in others...not so much.
"by Jack (September 18, 2010)
It actually works ok if you're patient with it. Nice work."