Wallet Wall works because RFID is highly susceptible to interference from surrounding objects. RFID signals can easily be scrambled by either metal or water. And since a water-lined wallet is pretty impractical, RFID wallets are lined with a thin and flexible layer of metal that blocks signals.
Wallet Wall products look like any other wallet, purse or cardholder. Because lots of people want to protect themselves against data theft, there’s a wide range of RFID wallets available in many different styles. They aren’t any more expensive than standard wallets, either.