This low cost RFID module is perfect for connecting to an Arduino.  It connects via a 9600 bps UART serial connection and outputs the tag number when an EM4100 compatible RFID card comes near.  Perfect for access control projects.

• Includes external antenna
• Maximum effective distance approx 5 cm.
• Less than 100ms decoding time
• UART interface (5 Volt TTL RS232)
• Support EM4100 compatible read only or read/write tags
• Small outline design (3.85cm x 1.9cm)