Keri MS Format vs. Keri 26-Bit: Which System Do You Have?

Keri Systems has two distinct card formats in active use across North America, and they are not interchangeable. If your system uses Keri MicroStar readers, you need Keri MS format cards — compatible by specification with the KC-10X and MT-10X OEM part numbers. If your system uses standard Wiegand readers on a PXL-250 or IntelliProx 2000 controller, you need standard 26-bit Wiegand cards — the open H10301 format compatible with KC-26X OEM credentials. American Key Cards supplies compatible, non-OEM cards for both formats, programmed to your facility code. But ordering the wrong one means cards that simply will not read, so confirming your format before you buy is the most important step in this process.

Why Keri Has Two Incompatible Card Formats

Keri Systems built its MicroStar product line around a proprietary 125 kHz protocol designed to work exclusively within their reader ecosystem. This was a common approach in the 1990s and early 2000s when access control manufacturers routinely created closed systems to maintain aftermarket revenue. The result is a format — the MS format — that Keri has never publicly documented and that no standard Wiegand reader will recognize.

In parallel, Keri also sells access control panels (notably the PXL-250 Tiger) that use entirely standard 26-bit Wiegand credentials, the same open H10301 format used by HID ProxCard, Farpointe Pyramid, and dozens of other brands. Cards for these systems are straightforward to source from any competent aftermarket supplier.

The confusion arises because both format lines run on the same 125 kHz frequency, and Keri sells both under the same brand. A manager inheriting a Keri system may not know which generation they have — and the card body labels rarely make it obvious.

How to Identify Your Keri Format in Under Two Minutes

Check the Reader Model

The reader is the fastest way to confirm your format. Look for the model number printed or embossed on the reader housing:

• Keri MS format: Readers labeled MS-3000, MS-5000, MS-7000, or MS-4000 are MicroStar readers. They use the proprietary MS protocol exclusively.
• Keri 26-bit (standard Wiegand): Readers labeled P-710H, P-900H, or any third-party Wiegand reader connected to a PXL-250 panel use the standard H10301 26-bit format.

Check the Controller Panel

If you can access the access control panel in the communications closet, the model number tells you everything:

• PXL-500P Tiger controller — MS format. Only MS-series readers connect to this controller.
• PXL-250 Tiger controller — Standard 26-bit Wiegand. Works with any Wiegand-compatible reader.
• IntelliProx 2000 — Standard 26-bit Wiegand pass-through. Use KC-26X-equivalent cards.

Check the Existing Card Label

OEM Keri credentials print the part number on the card label:

• Cards marked KC-10X, MT-10X, PKT-10X, or MT-10XP are MS format.
• Cards marked KC-26X, PKT-26X, or PSK-3 are standard 26-bit Wiegand.

If the card label has worn off or cards are unmarked, fall back to the reader model or controller panel as described above.

Format Comparison: Keri MS vs. Keri 26-Bit

Feature	Keri MS Format	Keri 26-Bit (Standard Wiegand)
Frequency	125 kHz	125 kHz
Protocol	Keri proprietary MicroStar	Open Wiegand H10301
Bit format	Proprietary (not publicly documented)	26-bit (facility code 1–255, card number 1–65,535)
OEM card part numbers	KC-10X, MT-10X, PKT-10X, MT-10XP	KC-26X, PKT-26X, PSK-3
Compatible readers	Keri MS-3000, MS-5000, MS-7000, MS-4000	Any Wiegand 26-bit reader; Keri P-710H, P-900H
Compatible controller	Keri PXL-500P Tiger	Keri PXL-250 Tiger, IntelliProx 2000, any Wiegand panel
Works in non-Keri readers?	No	Yes — universal compatibility
Cloneable?	Yes (125 kHz, low security)	Yes (open 26-bit, low security)
AKC compatible card	AKC Keri MS-Compatible Proximity Card	AKC Keri 26-Bit Compatible Clamshell Card
AKC compatible fob	AKC Keri MS-Compatible Key Tag	AKC Keri 26-Bit Compatible Key Tag

Keri MS Format: What You Need to Know

The Keri MS format is one of the most commonly encountered proprietary 125 kHz formats in legacy North American commercial buildings. The PXL-500P Tiger controller was one of the most widely sold mid-market access control systems in the early 2000s, and many of those installations remain in service today.

Keri has not published the technical specification for the MS protocol. However, the format has been reverse-engineered within the security research community, which is why compatible aftermarket credentials can exist at all. AKC’s Keri MS-compatible cards are programmed to operate correctly with MS-series readers — they are compatible by specification, not manufactured or authorized by Keri Systems.

What information you need to order Keri MS cards:

Because the MS format is proprietary, there is no user-accessible facility code in the same sense as standard 26-bit. When you order replacement MS-format credentials, you provide the card numbers currently in use in your system. Each card carries a unique number that is enrolled in your PXL-500P controller. AKC programs each card to the specific card numbers you specify. Contact us at /contact/ to discuss your current enrollment and what information your system needs.

Compatible readers for Keri MS format:

• Keri MS-3000 MicroStar Mullion reader
• Keri MS-5000 MicroStar Single Gang reader
• Keri MS-7000 extended-range reader
• Keri MS-4000 vandal-resistant reader
• All models connected to the Keri PXL-500P Tiger controller

Security note: Keri MS operates at 125 kHz with no cryptographic layer. While the bit structure is proprietary and was not intended to be reproducible, it carries no encryption that would prevent cloning with modern RFID research tools. This is consistent with the security level of all 125 kHz proximity formats from that era. If your organization requires higher credential security, consult your Keri integrator about upgrading to Keri NXT or MIFARE-based credentials.

Keri 26-Bit (Standard Wiegand): What You Need to Know

Standard 26-bit Wiegand — the H10301 format — is the most widely used access card format in North America. Keri’s PXL-250 controller and IntelliProx 2000 system use this open format, which means their cards are interchangeable with credentials from HID, Farpointe, and any other H10301-compatible supplier.

If you have a PXL-250 or IntelliProx 2000 system, you do not need a Keri-branded card. Any correctly programmed standard 26-bit credential will work in your readers and enroll normally in your controller software.

What information you need to order Keri 26-bit cards:

• Facility code (also called site code): a number from 1 to 255, typically printed on your existing cards or available from your original installer’s records
• Card number range: the sequential numbers you want programmed on the new batch

AKC programs each card to your exact facility code and card number. The resulting credential is functionally identical to OEM KC-26X cards.

Compatible readers for Keri 26-bit:

• Keri P-710H 125 kHz proximity reader
• Keri P-900H multi-format proximity reader
• Any standard Wiegand 26-bit proximity reader from HID, Farpointe, Kantech, and most other major brands

For more detail on standard 26-bit Wiegand and how facility codes work, see our Indala FlexPass 26-Bit format page for a practical comparison of another 125 kHz format that often gets confused with open Wiegand — and the Keri NXT format if you suspect your system may have been upgraded to the encrypted NXT protocol.

The Third Keri Format You Should Know About: NXT

A small but growing number of Keri installations have been upgraded to the Keri NXT format, which also operates at 125 kHz but uses an encrypted card-to-reader protocol. NXT credentials use a 96-bit encrypted handshake — a standard 26-bit card will not read in an NXT reader, and an MS-format card will not read there either.

If your readers are labeled NXT-1R, NXT-3R, NXT-5R, or NXT-6RK, you have an NXT system. This is a third distinct format from both MS and standard 26-bit. NXT credentials must be factory-programmed to the NXT protocol; they cannot be reproduced with generic 125 kHz cloners. AKC supplies factory-programmed NXT-compatible credentials — see the Keri NXT format page for details.

Why Non-OEM Keri Cards Cost Less

OEM Keri credentials are sold through a dealer network with the associated margin layers built into the price. A property manager or facilities director buying directly from Keri or a Keri integrator pays distributor markups at every level of that chain.

American Key Cards is not affiliated with Keri Systems. We supply compatible credentials by specification — cards programmed to operate identically to OEM originals at the electrical and protocol level, without the overhead of the OEM distribution network. The savings are real and consistent. What you do not get is the Keri brand name on the card body, which has no effect on whether the card reads or how reliably it works.

Getting the Right Keri Card: A Quick Decision Guide

1. Check your reader label. MS-3000 / MS-5000 / MS-7000 / MS-4000 → order MS format. P-710H / P-900H → order 26-bit.
2. Check your controller. PXL-500P → MS format. PXL-250 / IntelliProx 2000 → 26-bit.
3. Check your existing card label. KC-10X, MT-10X → MS format. KC-26X, PSK-3 → 26-bit.
4. If your readers say NXT → see the Keri NXT guide, not this article.
5. Still unsure? Contact us with the reader model number or a photo of the reader label and we will confirm the correct format before you place an order.

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Ready to order? American Key Cards ships Keri MS-compatible and Keri 26-bit compatible cards and key tags programmed to your specifications. Reach out through our contact page with your reader model, controller type, and the card numbers or facility code you need — we will confirm the format and get your order moving.