RFID blocking card holders are made to help you to be safe from a new type of thiefs, so called RFID skimming.
The reason is that some credit cards now have a built in radio frequence identification chip.
The credit card pocket for mobile phones have for a long time been a popular product. We now take it to the next level!
Selfadhesive tape on the backside
Remember to clean the surface the product is to be attached to.
Oil-based/greasy surfaces such as silicone have poorer adhesion, which has to do with the nature of the material.