As Seen On Paranormal Challenge & Ghost Adventures:
What makes the Mel-8704R-500 Model so uniquely different from all other EMF meters is that in addition to detecting AC/DC EMF fluctuations and ambient temperature changes, it has a special REM and ATDD feature. REM stands for Radiating EM Field. The Ambient Temperature Deviation Detection (ATDD) monitors Hot & Cold spot changes and converts the changes into an Audible Alarm using a One Octave step for each degree change, thus allowing your ears and others to easily discern each degree change. When the REM circuit is activated, an independent discreet EM field is created around a mini telescopic antenna.  See Illustration A.

                                                          Illustration A

                                                             REM Field Around Antenna

The REM field can ONLY be influenced by materials and objects with high electron mobility (many free electrons) in other words conductive properties. The types of atoms in a material determine conductivity. Based on Conductive source, proximity & strength, the EM field can be easily changed causing some field distortion. When this happens, there are (4) colorful LED lights and Sound that will activate. The visual and audible response is proportional and correlates directly to the REM field disturbance. The stronger the influence within the REM field, the more  intense the LED's and Sound response. The REM feature is immune to Radio Waves, AC/DC EMF and other nuisance influences that may lead to a false positive response. For best results, Place the device on a non-conductive surface when conducting your communication sessions. The Mel-REM can also be used as a hand held device, but careful attention should be made to keep hand and fingers toward the bottom of the instrument. Note: All features may be used independently or simultaneously. This instrument is intended to further help promote and advance Paranormal research.