VLF means Quite Very low Frequency and is similar technologies used in detectors designed for coins, jewelry, and relics. VLF detectors broadcast at frequencies measured in kilohertz ranging from three kHz to 70 kHz. Listed here are 5 explanations why you could possibly go with a VLF about a PI http://family.bigbrother.bg/forum/topic_show.pl?tid=238941;msg=NewPost;sid=62e34f56b6afecc56963bb66c221054b