I have learned to calibrate my ear and have gotten better with this compadre, but I continue to have a newbie question. I have been mainly using it at old school properties and old parks, I can recognize scratchy little iron, harsh and loud scraps of aluminum or pull tabs, etc, but there is lots and lots of tiny foil gum wrappers and shreds. Generally they don't fool me, but very often they come in sounding clean, repeatable and round like a deep silver coin, They disc at about the same as a deep silver coin. I don't mind digging a lot, but this is a bit of a problem, too many of those tiny foil signals.