If you a talking about the elliptical concentric I believe you just made a very smart purchase.
I have the one that came on my F70 and you couldn't take it away from me if you had a gun.
Let me tell you a little bit about my experiences.
When I got my F70 it was a little similar to my F2 but with so much more power and possible settings it was also a lot different.
For several weeks I was a total newb with this thing, had much more jumpy numbers and other behavior I was not used to but I still had fun going out there learning on every hunt.
The very first hunt I had with it in Kansas I picked up tons of coins and had a great time.
I was tired and pretty much near the end if my hunt when I decided to hit one last area in the park I was at, the outfield of an old baseball field.
Been there before, not much around here but I figured what the heck.
I was in 4H tones and I just ran around the field swinging way to fast like a hockey player on a fast break but didn't really expect much of anything.
I did come across a couple of coins, I was surprised I even got a signal as fast as I was sweeping, and then I got another high tone dime number signal that stopped me in my tracks.
Loud, clear, distinct as as a fine made bell, I stopped to examine it further and my pinpoint depth says 6".
Deeper than the other clad coins I found so I had to dig it and at least see if the depth was at least close.
It actually was exactly right on the depth call and it was not a coin but a tiny piece of bent up jewelry, a Chai pendant that was hit by a mower.
When I saw the tiny 925 I smiled...first hunt ever and silver!
To get such a great hit on something so tiny and deep with the coil moving so fast over it was I believe the first time my jaw dropped using my new tool...but not the last.
It was about on my third hunt, no more than the fourth later I was at another park near a picnic pavilion in an open area a little ways away that also had some tables...and tons of trash.
I was still plucking out some coins here and there, some trash to because everything was still a bit jumpy for me and I hadn't got the hang of narrowing that down just yet.
I was in 4H again and I ran over another signal that jumped several numbers but I heard a quick, sharp, clear high tone so I stopped to swing over it some more.
Numbers jumped from foil to mid nickel but heard a lower foil tone plus that nice high tone showed up if I moved the coil just right.
I dug a hole and saw a ring...and got excited.
This was on December 2nd 2013 and that was the year my great quest for gold.
I had found 3 gold rings by March and then set a ridiculous goal to find 12 that year in the dirt...one for each month.
Never thought I would do it, 6 was my average year total, but by December I had 11 and was desperate to find one more before the bad weather rolled in which was forecasted in just a few days.
This thing was one of the only gold rings I ever dug that was a dead on nickel signal out of the ground but in the ground it was jumpy because there was at least one if not two pieces of trash close by...and I mean within an inch or two.
I was thrilled!
No marks but it was huge and I know that resizing is one thing that can wipe out marks on rings so I stopped at a jewelry store to have it tested.
The very young girl took it in the back to test it for me and came back and said it was a combination white and yellow gold that tested 14k.
Then she offered me a lowball $85 to buy it from me and I said no thanks.
After posting a pic on another forum another member told me he located a ring exactly like this one for a friend that lost it, same white and yellow configuration, same odd shape which was not round but flattened in the rear, and this one was not 14k but platinum and 18k.
I still haven't got a test kit but I still have that ring and one day I think I am going to keep it for myself once I find out for sure.
It is way to nice for melt and I don't think I want to sell it even if I could get several hundreds for the thing.
It fits my fat fingers pretty good, also.
https://m.youtube.com/watch?v=FA3QNhLvvXw
There is something different about this coil I have come to realize after spending countless hours with it and also my DD's.
The response is so crisp, so fast, so precise that I can now tell a difference between that and my DD's.
You have to use both for awhile to hear and notice it but there is a difference and once you realize there is one you can sense it is not so little.
I can only describe the unique response on this one as one word...sweet.
Mike Hillis knows what I am talking about, he is a big sound guy and jewelry hunter and tried an F5 similar coil on his higher end Fisher and it worked fine but he knows what a coil like this is capable of and ordered a new concentric coil in the correct frequency just so he could take advantage of all of that sweetness.
This coil is not just fantastic on jewelry, coins and everything else come in great.
The depth I had in the mild soil in Kansas was about 10" at the high end, not as far as the big DD but enough to find every great coin or piece of jewelry I have ever found.
Using it in extremely heavy iron it worked just about as well as my sniper, hunting around heavy park trash also.
That squished configuration seems to almost to mimic the long thin scanning field of a a DD.
As far as pop tops a total non issue using this one.
Here in my very bad soil it goes as far and deep as my big DD easily, and with both of those and my sniper I have figured out a way to understand targets deeper here in the super bad soil infused with so much iron.
I was told when I got my F70 and then told people I was getting a small and a big DD that I would never use that elliptical again.
Not true...not true at all.
Those that think that way either never used one enough to hear or care about that difference, or don't hunt the way I do in my kinds of sites.
I switch to it from time to time for specific reasons like pop top infested sites, but also just as a change of pace and the more I used it the more I understood the uniqueness of that coil.
Now every time I put it on the first signal I get on a hunt I listen to that sweet tone and smile.
Sound is a big thing for me, I would never give this coil up for that and so many other reasons.
There...now you have heard of at least one person having great success with this coil and one that knows it so well he will never ever give it up.
HH