VLF means Incredibly Lower Frequency and is the same technology Utilized in detectors designed for cash, jewellery, and relics. VLF detectors broadcast at frequencies measured in kilohertz ranging from 3 kHz to 70 kHz. Here's five explanation why you may pick a VLF more than a PI The GPZ 7000 http://leydis16.phorum.pl/viewtopic.php?p=1009624#1009624