There has been a growing concern about privacy and security after the implementation of radio-frequency identification (RFID) in access cards, credit cards, passports and other devices which contain sensitive information. The only way to ensure the electronically stored information doesn’t fall in the wrong hands is to use an object with RFID blocking abilities. For cards and passports that would mean obtaining a sleeve or specifically designed wallets or passport holders.
The only way to prevent the information stored on the tags in your cards or passport from being scanned is to not let it be emitted in the first place. Many nylon, leather, and ballistic nylon wallets and passport covers have an aluminum sheet embedded into the lining which doesn’t allow access to the stored information while the case is closed. RFID sleeves achieve the same goal without needing to replace the wallet. Another solution is to use a case made from aluminum. Many prefer this, due to the superior protection an aluminum case provides.