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RFID Card Reader Serial

Reads 125 kHz Tags, EM41000 Family
Power requirements: 4.5 to 5.5 VDC
Communication: Serial at 2400 baud (8N1)
Dimensions: 2.45 x 6.25 x 0.22 in (62.2 x 82.5 x 5.57 mm)
Operating temp range: -40 to +185 °F (-40 to +85 °C)

Tags can be borrowed here at the SmartXp

manual
column on RFID

Code for using the Arduino with the Parallax RFID reader
Parallax RFID Reader <--> Arduino