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. 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. Model 1 operates on a standard 9-volt battery, and Model 2 runs on a 9-volt battery or an AC adapter (both included). Model 2 has an input jack for an optional high-sensitivity magnetic coil.