A k2 meter measures EMF which stands for electro magnetic fields. K2 meters are primarily purchased and used by those interested in the paranormal. More specifically, k2 meters are a popular tool used by ghost hunters because they believe that ghostly spirits or entities have electromagnetic fields that could be detected.
K2 EMF meters are today in demand, why because they are used to detect ghost presence.But they are often mistaken, they usually give difference in emf reading which can also be due to mobile and wiring around.
In my opinion it is a very superstitious beliefe that a meter can know a ghosts appearence. The producers of this equipment says the magnetic fields are known the ghosts and destroy its led also. But I don't believe an equipment recognize ghosts.