Here is the thing with the Golden Mask 4WD and the Golden Mask 7 and the Vista X, you can take a piece of aluminum foil and set them up to disk out the foil then once you have the foil disced out so they are not seeing the foil and not giving a tone on the foil then take a dime, nickel, or quarter and wrap any of those coins in that piece of aluminum foil and those three detectors will then give a tone on the coin they will all three do the same thing with those coins setting under a pile of nails and the coins not seen, do not ask me how they can do that but they absolutely can do that, I have tried these test based on a video I seen that was put out by Paul Warren after I received my Vista X and I have done those same test with every beep and dig I currently own and with the Digital Cell phones on a stick detectors I own and ones I have borrowed and none of the digital's can even come close to performing on those test like the Analogs
I will find Paul's videos and link a few of them for you