IF you have a credit card that has what looks like a WIFI logo anywhere on (See below) it is an RFID card. Reality is, most cards are NOT RFID yet so, you may have nothing to worry about. However, if you do have an RFID card (or cards) simply place it/them between these 2 RFID blocking cards, and you'll be all set. The RFID blocking cards are a perfect solution for the WOBO! While the cost of these thin RFID cards sold separately are $5 (for 2), it's only $1 when purchased with a WOBO.