VLF stands for Quite Small Frequency and is similar technology Utilized in detectors developed for coins, jewelry, and relics. VLF detectors broadcast at frequencies measured in kilohertz starting from three kHz to 70 kHz. Here's 5 main reasons why you may choose a VLF in excess of a PI Benefit http://nec.phorum.pl/viewtopic.php?p=746184#746184