13.56MHz RFID/NFC Card – 1KB

These blank RFID/NFC cards works on 13.56MHz  frequency and are used widely in train/bus passes but also found in other systems like office access control systems, where a proximity card is desired. The tag contains a small RFID chip and an antenna, and is passively powered by the reader/writer when placed a couple inches away.It will work with almost any 13.56MHz RFID/NFC which can handle ISO/IEC 14443 Type A cards as there are a few other encoding standards (like FeLica). These are tested and working great with Adafruit PN532 NFC/RFID breakout board and Adafruit NFC/RFID Shield for Arduino!

These chips have memory 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 MIFARE Module and RFID Evaluation shield  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 a ISO/IEC 14443 Type A 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 it. This only matters if you're trying to use this tag with a phone/tablet.

RFID chip specification:

Image and Contents from Adafruit