Without getting caught up in the technical details, Pulse Induction metal detectors or PI detectors can reach far greater depths than VLF metal detectors, but each type of detector is designed for a specific activity.
Pulse induction metal detectors are best suited for searching for large objects at great depths (up too 8-10 meters, depending on the power and coil used).
Besides reaching great depths, when used with large rectangular coils, pulse induction metal detectors also have the advantage of being immune to soil mineralization or small metallic junk objects (nails, tin foil, bottle tops).
The disadvantage of pulse induction metal detectors is the lack of discrimination between ferrous and non-ferrous metals (this has been addressed by Detech technicians). PI detectors are not the best choice for beginner detectorists and the use of large rectangular coils requires two people.
PI detectors are not appropriate for searching for coins, small jewelry or scattered relics.
They are however best suited for searching for large objects at great depths, such as treasure, large coin spills, artifacts, pipes, tanks, shells (all at great depths, that VLF metal detectors can not reach) and more!