I dug a piece of what seems to be gold plated jewelry 12-24-12, it looks like a lawn mower got it at some time, it rang in the 40's @ 4in. now this was small about 1/8 wide and 1/4 long, when I finally separated it from the dirt it looked like gold, further investigation seems to be gold plated, also I found a piece of brass very small a few weekends ago that was the size of a small needle bearing, I have one of the newer AT Pro's, it is my understanding from those who have or got the older one's , are not satisfied with them and I can not blame them, it's like buying a car without a motor, but running this thing in Pro mode either custom or I prefer zero mode, it is sensitive, also when I ground balance in Auto, I'll back off 5 points or so, I'm still learning, so this is not professional advice at all, I can only speak and testify my experience so far...but it does ring in small objects,, also I use the 5x8 coil....