The peice is not as thick as the penny but is close on half of it. I took it the creek today, and found alot of nails, pull tabs, and bottle caps. O and a big ball of foil. I was able to GB it very quick. I would like to see it get more responseve toward the gold. Its kinda quite. With the four inches is just an esstimate air test. Down by the creek, it did ok it did gb good, and was a little chipy, but was able to find a lot of targets with it. I must of found 20 items in 45min to an hr. IT was junk, but found alot of stuff. Well getting ready for day 2 with the gold bug...