This app works like a portable metal detector. By detecting nearby electromagnetic fields using the phone's built-in magnetometer/compass, you can locate nearby metal and magnets. You can also use it to find metallic studs and wiring behind walls. Works with only magnetic metal (steel, iron etc).

The magnetic field level(EMF) in nature is about 49μT(micro tesla) or 490mG(milli gauss); 1μT = 10mG. You will see this value by default.