Made Of PET Outer Material With Aluminum Inner Adheres To Back Of Your Phone With Strong Adhesive Place Your Credit Card In Holder To Prevent Cyber Hackers From Stealing Your Identity Prevents Data Transfer Between The Wallet And Reader Works With Any Contactless Chip Card. Cards That Are Swiped Do Not Send RFID Signals And Will Not Be Protected By An RFID Blocker Size: 2 ½" W x 3 ⅝" H