Why does the exact format matter before you order?
Access credentials are not interchangeable. A card that looks identical to yours can be completely invisible to your reader if the chip, frequency, or bit format is different. Two cards can both be white PVC with no visible electronics and still operate on entirely separate technologies, so judging by appearance alone is unreliable.
Getting the format right the first time saves a wasted order and a return. A compatible credential has to match the radio frequency your reader listens on, the chip family your panel was programmed to read, and the data structure — the Wiegand bit format or the smart-card application — your system expects. Identify all three and ordering a compatible replacement becomes straightforward.
How do I read the printed part number and markings?
Start with the card itself. Manufacturers usually print a part number, a model code, or a short hex/decimal ID somewhere on the surface, often in small text along an edge or in a corner. On many cards you will also see an internal ID number and a separate external (printed) number, sometimes called the facility code and card number — exactly the values we encode to so a replacement reads identically on your existing readers.
Hold the card up to a bright light. Inductive 125 kHz cards typically show a coil of fine wire wound around the inside edge, while a 13.56 MHz card shows a smaller squarish or rectangular antenna loop with just a few turns and a tiny chip module. That visible antenna shape is one of the fastest ways to judge the frequency before you confirm it.
- A long part/model code (letters plus digits) — note it down exactly, including any prefix or suffix.
- Brand or logo silk-screened on the card or fob body.
- A printed ID number, and whether there is a second internal number.
- Antenna style under a light: many fine coil turns suggests 125 kHz; a small few-turn loop suggests 13.56 MHz.
How do I tell 125 kHz from 13.56 MHz?
Frequency is the single most important fact to nail down. Low-frequency 125 kHz (LF) covers the classic proximity world: HID Prox, EM4100/EM4102, Indala, AWID, and many building and gate systems. High-frequency 13.56 MHz (HF) covers smart cards: MIFARE Classic, MIFARE Plus, MIFARE DESFire, HID iCLASS, Seos, and most hotel and transit credentials.
If the printed markings name a chip you can search, that settles it. EM4100, EM4102, EM4200, T5577, or HID Prox point to 125 kHz; MIFARE, DESFire, iCLASS, Seos, NTAG, or iCODE point to 13.56 MHz. When nothing is printed, the reader and your phone (next section) usually give you the answer.
What does the reader by the door tell me?
The reader mounted beside the entrance is often the clearest single clue, because its brand and model usually match the credential technology it was sold with. Look for a logo and a model number on the reader's face or on a label on its back or bottom edge. HID, Indala, AWID, Software House, Lenel, Kastle, Gallagher, Inner Range, ProdataKey, and hotel-lock brands such as VingCard all stamp identifiers you can note.
Some readers are multi-technology and accept both 125 kHz and 13.56 MHz, which is common on newer installations and dual-frequency systems. If the reader brand is one of those, your card could be on either frequency, so confirm with the card markings or a phone check rather than assuming.
Can I check the card with my phone?
Yes — for 13.56 MHz cards a phone is a quick first test. Most modern Android phones with NFC enabled will detect a 13.56 MHz credential when you tap it to the back of the handset; an NFC reader app can often report the chip type (for example a MIFARE or NTAG tag) and the card's UID. Note that NFC phones cannot read 125 kHz proximity cards at all, so a no-response on the phone is itself a useful hint that you are probably holding a low-frequency card.
You do not need any specialist equipment to order from us. If you are not sure after the steps above, the printed markings, the reader brand, and a quick phone tap together are usually enough for our applications team to identify the exact format and confirm the matching compatible product.
- Phone NFC tap: reads 13.56 MHz only; reports chip type and UID on many handsets.
- No phone response often means a 125 kHz LF proximity card.
- The card markings plus the reader brand together pin down most formats.
- Still unsure? Send us photos and we will identify the match for you.
What can we supply once the format is known?
Once the format is known, what we supply depends on whether the credential is an open or a secured technology. Open formats such as EM, HID Prox, Indala, AWID, and legacy iCLASS standard configurations are non-proprietary, so we encode a compatible credential that presents the exact data your readers already accept — same frequency, bit format, facility code, and card number. The result is a spare or replacement card or fob your reader treats identically to the original.
Secured smart credentials such as MIFARE DESFire with AES, HID Seos, and iCLASS SE or Elite are protected by design. For those we supply compatible blank credentials on the matching chip platform, and your own access-control system or lock enrols them with its keys — exactly as it would credentials ordered through the OEM channel. The keys, and your site security, stay entirely in your hands. Security ID Systems is an independent manufacturer and supplier of compatible access-control credentials and is not affiliated with, authorized by, or endorsed by these manufacturers.
How do I order the right compatible card?
When you have your clues, match them to the matching compatible product page on this site by brand and format, or browse the catalogue by frequency. Most common office, gate, and hotel systems have a dedicated compatible product ready to order as a cost-effective alternative to OEM credentials, and bulk quantities are available on request. We also keep your format on file for fast reorders.
If anything is unclear, skip the guesswork. Email us a clear photo of both sides of the card or fob and a photo of the reader by the door, or mail a sample, and we will identify the format and point you to the correct compatible product. Tell us the brand printed on the reader and any part number on the card and we can usually confirm the match without a sample at all — and we verify compatibility before production.