EM4200 (128-bit Enhanced Read-Only) Compatible Cards & Fobs
EM4100 with more room and more reach: EM4200 offers up to 128 bits and better read range while staying backward-compatible with EM4100 readers in 64-bit mode — plus an ISO animal-ID mode for tagging.
Does American Key Cards make EM4200 (128-bit Enhanced Read-Only) compatible cards?
Yes — American Key Cards supplies unbranded EM4200 (128-bit Enhanced Read-Only) compatible cards and key fobs (AKC EM4200-Compatible Clamshell Card), encoded to your facility code and card-number range and ready to use on your existing EM Microelectronic readers. No hardware changes and no dealer account required.
- 125 kHz
- Frequency
- RFID prox
- Technology
- 2
- Bit formats
- 1+
- OEM part nos.
- American Key Cards
- Order from
EM4200 is the sensible evolution of the EM4100 family: same read-only philosophy, but with a larger ROM (selectable at 64, 96, or 128 bits) and a tuned resonance that gives noticeably better read range on the same readers. Crucially for anyone maintaining an installed base, it runs backward-compatible in 64-bit mode, so an EM4200 credential drops into an EM4100 system without touching a thing — making it a clean upgrade credential as older stock is retired. Its extended mode also speaks the ISO 11784/11785 FDX-B protocol used for animal and livestock identification, which is why the same chip family shows up on farms and in vet clinics as well as office doors. We supply unbranded, compatible-by-specification EM4200 cards and key tags programmed to your IDs and mode, verified before shipping — a longer-range replacement that your existing EM readers accept without reconfiguration.
EM4200 (128-bit Enhanced Read-Only) specifications
- System brand
- EM Microelectronic-Marin SA
- Technology
- Passive RFID proximity
- Frequency
- 125 kHz
- Credential platform
- EM4200 read-only IC: 128-bit ROM with selectable 64/96/128-bit output, enhanced resonance for longer read range than EM4100, ASK/Manchester, ISO 11784/11785 capable
- Bit formats
- 128-bit EM4200 protocol (selectable 64/96/128-bit output; EM4100/EM4102-compatible in 64-bit mode), ISO 11784/11785 FDX-B compatible in extended mode
- OEM part numbers
- EM4200
Specifications reviewed August 2026
Our compatible EM4200 (128-bit Enhanced Read-Only) credentials
American Key Cards manufactures unbranded credentials engineered to work with your existing EM Microelectronic readers — no hardware changes, encoded to your facility code and card-number range before they ship.
Full specifications, form factors and ordering FAQ: Standard 125 kHz proximity cards
American Key Cards is an independent manufacturer of unbranded, compatible-by-specification credentials. We are not affiliated with, endorsed by, or sponsored by EM Microelectronic, and we never supply OEM-branded product — for brand-original credentials, order from EM Microelectronic or an authorized dealer. Brand names appear only to identify compatibility, and all trademarks remain the property of their respective owners.
Where EM4200 (128-bit Enhanced Read-Only) is used
- Upgrade path from EM4100 systems needing longer read range
- Animal and livestock identification (ISO FDX-B mode)
- Basic door access where read distance matters
- Time-and-attendance and visitor tracking
- Parking and asset management
Works with these readers
Related formats
You might also need
EM4100 (64-bit Read-Only)
The world's baseline 125 kHz credential: EM4100's 64-bit read-only ID, transmitted in Manchester-encoded ASK, is what most simple prox systems, time clocks, and gym doors actually run on.
View compatible cardsEM4102 (64-bit Read-Only Variant)
EM4100's identical twin: EM4102 transmits the same 64-bit read-only protocol, so the two are interchangeable on any EM-protocol reader — a detail worth knowing so you don't overthink a reorder.
View compatible cardsHID Prox H10301 (Standard 26-Bit)
The most widely deployed proximity format in North America: 26-bit Wiegand — an 8-bit facility code plus 16-bit card number — on the 125 kHz HID Prox platform, live on millions of doors.
View compatible cardsEM4200 (128-bit Enhanced Read-Only) — FAQ
How does EM4200 differ from EM4100?
More memory (up to 128 bits vs 64) and better read range from an improved resonance design, while remaining backward-compatible with EM4100 readers in 64-bit mode. It also adds an ISO FDX-B mode for animal identification that EM4100 lacks.
Are EM4200 cards backward-compatible with EM4100 readers?
Yes, when programmed in 64-bit output mode — they read on EM4100 infrastructure identically, which makes EM4200 a drop-in upgrade for facilities wanting more range without changing readers.
Can I use EM4200 for livestock or pet tagging?
Yes — in its extended mode it supports the ISO 11784/11785 FDX-B protocol that animal-ID readers use. Tell us the application and we program the correct mode (access-style ID vs FDX-B) for your readers.
What do you need to program a batch?
Your enrolled IDs (or a request for fresh sequential ones), the output mode your readers expect, and form factor. A sample credential or your access-software export confirms the specification before production.