I have found coins and silver and gold jewelry with the standard coil.
Great for all around hunting.
I have found coins and silver and gold jewelry with the 11" DD coil.
One 14k gold ring was found in a large area while swinging way too fast and literally running around this site looking for just one great target before I left.
I still believe the speed of the Vaq and the large scanning field on the coil was the reason I found it.
Paid for the coil and then some with that ring.
The large DD is great for hunting big wide open areas.
I have found coins and silver and gold jewelry with the 5.75" concentric.
Pop tops are not an issue with this one, depth is great and perfect for hunting in trashy areas.
In mineralized soil the DD version, in good soil the concentric is what I prefer.