Which might be handy if you’re searching in a location with, say, loads of aluminum pull tabs, but you would like to find things designed only of brass or gold. (I buried my gold wedding day ring—tied to a protracted string—together with a steel bolt for this examination. Found it!) https://collinoboyk.uzblog.net/helping-the-others-realize-the-advantages-of-metaldetector-42765289