Took the Pro for a swim today and got a signal that I could hardly find in my float. Yes it drove me crazy, but I found it!! This VERY SMALL AND VERY thin broken piece of chain. I believe it's silver and has been in the water for a very longgggg time. The pro gave a good enough beep for me to dig it. The item in the middle is actually a toothpick to show how thin this piece of chain is. Also included a picture with a penny for size comparison. Man this Pro is sensitive, JMO
JOE in MD
JOE in MD