VLF stands for Very Low Frequency and is the same technological know-how used in detectors created for coins, jewellery, and relics. VLF detectors broadcast at frequencies measured in kilohertz ranging from 3 kHz to 70 kHz. Here are 5 explanation why you could select a VLF above a PI The https://castocus.com/blogs/48585/Power-Systems-of-Metal-and-Gold-Detectors