This is part of a post by Daniel in Tennessee from Dan Kankowski forum....if This infringes on someone's rights, please delete. Good news for gpx users... For the effective depth of the iron discrimination part...I have found this actually varies quite a bit in your overall settings AND coil used. I ditched the stock Commander coils and bought all DeTech coils for my GPX. I found a new site back in the spring while hunting with the 15 inch Spiral DD coil and it had a little more iron mixed