VLF means Really Small Frequency and is the same engineering used in detectors constructed for cash, jewelry, and relics. VLF detectors broadcast at frequencies measured in kilohertz starting from three kHz to 70 kHz. Listed below are five explanations why you may perhaps opt for a VLF over a PI http://taniecirlandzki.phorum.pl/viewtopic.php?p=120667#120667