This is a simple EMI/EMF detector and meter. The manual is availible in one of the images above.

This meter can detect EM fields emitted from most electronic devices. This includes power lines and cords, radio transmitters and much more.

This unit could also be used to locate a "spy bug" in locations where no electronics should normally be present.

We are not experts about this meter, or in the process of detection and measurement of EMI or EMF.