I put the 9 x 12 concentric coil on the AT Pro early in the spring, and have left it on all summer. I like the large coverage it gives me, and it just works great! Lots of trash in this park. It gets lots of traffic all year round. The large coil does surprisingly well in amongst the trash. I will soon switch to the 8.5" x 11" standard coil to see who they compare. Here's the finds......about 4 1/2 hours total hunting time. I am finding a lot of dimes this year which I missed last year with the Scorpion. I just love the audio of the AT pro.
Below are the rings....
