The name of RFID Clamshell Card comes after its clamshell appearance. It is one of the earliest RFID card form factors, widely adopted in access control field. Mostly encapsulated with EM-ID chip, like EM4200, TK4100, also can encapsulate T5577 and MIFARE chips. It is with similar size as the credit card, but about double thicker. Because of its thickness and it has more space to contain much thick and more powerful RFID antenna, it is widely used to produce long distance application.