My daughter had this for Christmas, after seeing it in a Toyshop, and going on about how fun it would be to find buried treasure..... well good luck, it struggles to find anything less than 1/2 inch away on carpet, let alone buried in something.
I chucked some coins on the lawn for her to find, and it struggled to find those unless you drop the dectector right on top of the coin.
(in fact we still can't find some of them!)
Poor, poor, poor - I wish I had returned it as not fit for purpose, espescially as its [...], not a cheap toy really...
I'm surprised as you expect the National Geographic brand to be a quality brand..... wrong!