Professional Pulse Induction detectors for very deep targets. These metal detectors emit powerful electromagnetic impulses that penetrate deeply in the ground. The depth of detection depends on the target size and the search coil size, and could go as far as 3-4 m below the ground surface. If you are an archaeologist or a serious treasure hunter, you must own such a machine. The PI detectors find targets that are unreachable for the hobby detectors. The treasures other have missed are waiting for you.