EMF meter

One of the most important piece of hunter equipment, the EMF Meter. The EMF Meter measure EMF (Electro Magnetic Feild), EMF is given off by spirits. So this helps hunters find if the room is haunted, or sometimes where the spirit's body is. Although, if there is nearby power lines, then the EMF meter is rendered useless. When EMF gets high, it makes noise.

Appearance
The EMF meter first appeared in Phantom Traveller when Dean made his own emf meter out of an old tape player. That creation was never seen again. They later switched to the one they use now, which is small and more unnoticable.

EMF meters don't always look the same. The Ghostfacers used a more squarism one, and a bit more larger than Sam and Dean's. But it works.

Fake ones have even been made in The Real Ghostbusters, when fans pretended to be Sam and Dean.