VLF means Quite Reduced Frequency and is identical engineering used in detectors built for coins, jewellery, and relics. VLF detectors broadcast at frequencies measured in kilohertz ranging from 3 kHz to 70 kHz. Listed below are 5 explanations why you could decide on a VLF in excess of a PI http://gzew.phorum.pl/viewtopic.php?p=623507#623507