VLF stands for Very Minimal Frequency and is identical technology used in detectors constructed for cash, jewellery, and relics. VLF detectors broadcast at frequencies calculated in kilohertz ranging from 3 kHz to 70 kHz. Here are 5 explanations why you might go with a VLF above a PI You can http://classichonda.phorum.pl/viewtopic.php?p=176963#176963