RFID-blocking wallets are an evolution of law-enforcement technology. Britz says these “Faraday devices” – bags, cages and wallets – act as an electromagnetic shield and are often used to protect electronic evidence. To get a peek at some of the devices used for forensics purposes, look at Faraday-Bags.com’s “Black Hole” line.
Britz notes that these types of items, including ones for consumers, are coming down in price. ThinkGeek.com’s offering runs about $20.