The Tracker IV is an old time favorite of mine! It has 3 modes-a/m, normal discriminate, and tone discrimination. By setting it on tone and rotating the dial from off position until a nickel gives a solid low tone, you will have a fairly accurate form of notch discrimination! Nickels/large foil will give a low tone, old style tabs and aluminum will give a broken hi/lo tone, and clad a high tone! And setting the sensitivity at 3/4 will give some great depth in normal ground. My FIFTH one was stolen and on some sites I really miss it!
AND it is a product of a great mind- George Payne- a pioneer in technology!
Just ordered it on amazon, i'm excited .
Also, the air test wasn't accurate it seems. I buried something 7 inches down and it was able to pick it up.. idk lol