Product info:

1) RFID module based on MFRC522 chip.
2) Support Mifare family card and ISO14443 Type A card.
3) Operating voltage: 3.3 Vdc.
4) Operating frequency: 13.56 MHz.
5)Operating distance: 4cm (card), 2cm (token).
6) Communication interface: SPI.
7) Power LED indicator.
8) Pinout:
                SDA = NSS = Chip select
                SCK = Clock input
                MOSI = Master out slave in
                MISO = Master in slave out
                IRQ = Interrupt request
                GND = Ground
                RST = Reset
                3.3V = Supply input

9) Dimension: 39 x 60 mm.
10) Weight: 22g.
11) Product code: ME000058.
 

Reference:

1) http://www.electrodragon.com/w/index.php?title=RFID_Card_Reader/Detector_Module