CH Hanson 03040 Magnetic Stud Finder

From the Manufacturer

Positively locates nails and screws with powerful \"neodymium\" magnets. The magnetic stud finder works like magic. It sticks to the wall leaving your hands free--no batteries, no calibration, no lights, no hassle. It works on wood or metal studs, and uses multiple industrial strength magnets to “Field Vector” the stud. This is the last stud finder you will ever buy. Simply slide the flat surface of the magnetic stud finder slowly across a wall in a circular or \"S\" motion until you feel a strong pull to a nail head or screw. Once you have the magnetic stud finder directly above a nail head or screw, let it go and it sticks to the wall.