There is definitely no shortage of EMF meters available, from KII's to Mel meters and everything in between. Once again, what you use should be dictated by personal preference and budget. We personally look for meters that have the ability to give an audible and visual alarm. Meters also come in analog or digital format.
These are examples EMF meters we have in our inventory. From left to right: an E.L.F. Zone EMF detector, this gives you 3 levels of readings and can be useful in interactive situations. The next is an inexpensive EMF meter from China and costs about $12. Next is the Ghost Meter. These have an analog meter up to 5 milligauss but have both a visual and audible alarm. We utilize a lot of these, especially in static positions where a camera can monitor them.
EMF meters are used during an investigation to detect anomalous energy signatures. It is believed that this energy is generated by the spirits and usually can be tracked with EMF meters as it moves through an area. Before an investigation starts the investigation area should be base-lined with EMF meters to establish a value that can be compared to during the investigation. Sometimes during the baseline process an area will be discovered with high levels of EMF. It is advisable to determine the source of the high EMF and report it the client if it is something that needs to be repaired. Sometimes a situation will be found where power going through the walls will cause high EMF in a room. This is typically referred to as a fear cage. High levels of EMF can adversely affect
a person. Effects can be from hallucinations to causing paranoia.
You can find a large selection of EMF detection equipment at GhostStop.