Hello and greetings, I read the proximity tag of the office for Flipper and I want to insert it right now into a blue proximity tag like the existing one and I want to buy from AliExpress, I understand that there are several types, I would like to receive a recommendation on what to buy to write RFID 125khz or nfc on it, thank you very much
RFID 125khz and nfc are not the same, we generally speak of NFC for high frequencies (13,56MHz); RFID is for 125kHz which is a low frequency. (but you can find key fobs having both chips on it)
For the RFID part, you need to buy key fobs having a T5577 chip.
But Iโve experienced that some vendors are saying T5577 into description, but itโs not. (I tried amazon, not aliexpress)
Good luck 
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Thank you very much for the answer, I ordered and am waiting for it to arrive
Just by the way, what is the type EM4100
I just copied the chip and it says EM4100 [EM MICRO]
Do you think I need a T5577 chip for this?
Thank you very much
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Yes.
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