Stinky Pete

With the concentric you can certainly use iron reject seems to work well

you can switch to mono for pin pointing as the outside becomes live and sensitive 

Regards Pete 

Hi I'm the distributor for Detech in Australia.

We have been having great success with the Detech range of coils.

Australian prospectors have been keen to purchase these competitively priced coils.

And have most certainly given us positive feed back on the build quality and performance.

The range of coils have been extensively tested in the Australian gold fields, all new coils are tested here before we release them.

Most of the feed back is on how sensitive the coils are and how they go about there job so quietly .

These are robust coils 100 percent waterproof and very resistant to bump or touch sensitivity

We've had great customer feed back

The Detech range is still evolving

Hope this helps

Stinky Pete Australia

Detech-metaldetectorsaustralia.com.au