I would hunt at foil disc-on mine just set the knob pointer where it's above "iron" and dig everything. The "trashy" signals will have more of the chopped signal for you to learn easier. The "good" signals-and this includes pulltabs will have either a longer, smoother sound. The probable trash signals will sound as if the front and back of the signal have been chopped off or only give a strong sound one way. Then, after you get used to the different sounds, you may want to lower it all the way to zero-which is still rejecting nails,small iron but gives you the chance to find small gold items. It's hard to do this sometimes, as the small pieces of foil and other "pesky" trash are pretty well eliminated at just below nickel and you can still get 75% of the rings.