VLF stands for Really Lower Frequency and is the same know-how used in detectors designed for cash, jewellery, and relics. VLF detectors broadcast at frequencies measured in kilohertz starting from three kHz to 70 kHz. Here are five main reasons why you would possibly pick a VLF around a PI http://family.bigbrother.bg/forum/topic_show.pl?tid=238942;msg=NewPost;sid=9e961f25ee0fc1cc803690bbc04e8e1f