Quality and functionality:
It is ultra-thin and thanks to elastic bag fits in more than just a cash card.
The bag (glue on the back) should be removable without residue - which I have not checked, because I was honestly too delicate. I have placed the only times to the sample on the smartphone, to show how it might look like (see photo).
However, I have found a solution for me: I'll glue the CHARITIK bag on a mobile phone shell and can therefore still be used, without leaving adhesive possibly damage to the smartphone. Because of the small stuff the bag is perfect.