E-Field Technology anti skimming card non-electronic data theft (rfid blocking card / shield card/ rfid anti-theft card / Skimming Card ) The blocking card is the size of a credit card that is designed to protect personal information stored on high frequency (13.56mhz) smart cards such as credit cards, debit cards, identification cards, passports, membership cards and so on. The blocking card needs no battery. It draws energy from the scanner to power up and instantly creates an E-Field, a surround electronic field making all 13.56mhz cards invisible to the scanner. Once the scanner is out of range the blocking card de-powers. Simply carry this blocking card in your wallet and money clip and all 13.56mhz cards within range of its E-Field will be protected.