These coils look amazing,very like the Nexus hoard hunter coils,I've just learned that a field test will be out soon,I'll post it here if I get first,should give incredible depth if they work good,let's hope they do!
you can see them here
http://www.joanallen.co.uk/a_metal_detector_accessories.html
you can see them here
http://www.joanallen.co.uk/a_metal_detector_accessories.html