TriField Natural EM meter XRB by Entity Electronics
The TriField Natural EM Meter was designed to do field measurements for special research. It detects changes in extremely weak static (DC or "natural") electric and magnetic fields, and signals with both a tone and the movement of a needle-type gauge if either the electric or magnetic field changes from previous levels.
Its sensitivity is of interest to researchers in the field of parapsychology. Every type of detectable physical manifestation requires a certain amount of energy. For example, “moving air” requires the expenditure of a small amount of energy to get the air to move initially. A radio and microwave detector is also included, which reads radio power directly. Because man-made AC electric and magnetic fields are very common and could interfere with readings of static fields, the meter has been designed to ignore AC fields. Normal construction materials don’t block magnetic fields, so the meter can be placed indoors and will work equally well, and due to the built-in tone, it can be used in the dark, and will sound the tone at whatever level of field the user sets. It operates on a standard 9-volt battery.