Before you can replace a fob, badge, or tag with an implant, you need to know what is inside it. The printing on the outside almost never tells you, and two credentials that look identical can run on completely different technology. Work through the three steps below and you will land on the right implant.
Nearly every access credential runs at one of two frequencies, and they are not interchangeable. A Dual Frequency Field Detector Keychain tells you which one you have in a couple of seconds: hold it in the reader field your card normally works with and see which LED lights.
If you only ever need to check one band, the single-frequency Field Detector Keychain and the larger 27mm Field Detector do the same job.
No detector to hand? An Android phone with NFC will read a high-frequency credential and ignore a low-frequency one entirely. That is a crude but usable test — if your phone sees nothing at all, you are probably holding low frequency.
The older band. Short range, rarely encrypted in practice, and generally easy to clone. Typical of building access fobs, apartment entry, gym tags, and older office badges.
Common chips: EM4100 / EM41xx, HID Prox, and T5577 — the last being a writable emulator that can be made to imitate most of the others.
Where to go next: EM41xx implants, HID Prox implants, T5577 implants.
The modern band, and the one your phone speaks. Supports encryption, larger memory, and NDEF data sharing. Typical of newer office badges, transit cards, hotel locks, and anything contactless-payment adjacent.
Common chips: MIFARE Classic 1k, MIFARE DESFire EV1/EV2/EV3, NTAG21x, ICODE SLIX, and HID iCLASS.
Where to go next: MIFARE Classic, DESFire, NTAG2xx, ICODE SLX, HID iCLASS, other MIFARE.
Frequency gets you to the right shelf. Getting to the right chip means reading the credential itself.
The Proxmark3 Easy is the tool that answers this properly — it identifies the chip type, reads the ID, and tells you whether the credential can be cloned at all. It is the same device your installer or a locksmith would reach for. For high-frequency credentials alone, the KBR1 Keyboard Reader and Blue Bambino will read an ID out to your computer without the learning curve.
Not ready to buy a reader? Bring the credential to your installation partner, or post a clear photo of both sides on the forum — between the printing, the shape, and the frequency, the community can usually name it.
Clone the existing credential. If the chip is one of the cloneable types, an implant can be written with the same ID and your existing reader will accept it with no changes at the door. Start at Clone a Chip.
Enroll a new credential. If you control the access system — your own home, your own office — it is usually cleaner to enroll a fresh implant directly than to clone anything. Any implant on the matching frequency will do.
Test before you commit. A Card Pack lets you check that a given chip type actually works with your reader before anything goes under your skin. This is the step most people skip and then regret.
Still unsure? Identify a Transponder collects the tools from this page in one place.