There are two different types, including electronic and magnetic stud finders. Electronic stud finders measure the capacitance in the wall, which is the amount of electrical charge that ma material is able to absorb. This measurement is higher when an electronic stud finder is moved over the wall where a stud is located. Magnetic stud finders, on the other hand, are powerful rare earth magnets that detect a metal screw or nail fastened to the stud. They’re easy to use and they never need batteries, but they are only as accurate as the screw or nail fasted to the stud.