Flawed

I decided, after much deliberation, to buy, what is effectively a zoom lens for my IPhone, but they call it a 8x magnifier.
Reduced by £10.00, too good to resist.
Indeed, and the quality is very pleasing.
Except, there is always something, there is a flaw . There is a little black mark, that is not on the lens, but inside the lens.
You can see it on the photo on the bottom left corner, where the support meets the rail.
I will have to change it next week some time, when I am in town again.