This is a blank MiFare Classic card - often used for train/bus passes but also found in other systems where a proximity card is desired. The tag contains a NXP S50 chip and an antenna, and is passively powered by the reader/writer when placed a couple inches away.

These can be read by almost any 13.56MHz RFID/NFC reader but make sure it can handle MiFare cards as there are a few other encoding standards (like FeLica) They are tested and work great with both our PN532 NFC/RFID breakout board and Adafruit NFC/RFID Shield for Arduino!

These chips can be written to & store up to 1 KB of data in writable EEPROM divided into banks, and can handle over 100,000 re-writes. You can use our PN532 NFC/RFID breakout board or Adafruit NFC/RFID Shield for Arduino to read and write data to the EEPROM inside the tag. There is also a permanent 4-byte ID burned into the chip that you can use to identify one tag from another - the ID number cannot be changed.

These use the S50 chipset, which used to be the 'classic' NFC chipset. In ~2014, the NFC forum decided not to support this chipset anymore, so newer phones do not support the MiFare classic. This only matters if you're trying to use this tag with a phone/tablet.

TECHNICAL DETAILS

S50 chip specification:

• 1 KiloByte (8 KiloBit) non-volatile EEPROM storage
• Built in encryption engine with 48-bit key
• 4 Byte unique identifier burned into the chip
• 13.56 MHz frequency

Tag specification:

• 85.5mm x 54mm x 1mm /3.36" x 2.1" x 0.03"
• 6.3 grams / 0.2 oz
• Works about 4" away from reader

Downloads:

NXP S50 datasheet