How the compatible Keri Systems MS / NXT (K-Format) works
The Keri Systems MS / NXT (K-Format) is a 125 kHz low-frequency proximity credential — the band most legacy prox readers use. Its data structure is Keri proprietary K-format / MS (Megastar) PSK - distinct facility-code ranges + internal mapping; NXT borrows Pyramid data structure ('N' prefix = NXT); FSK2 RF/50 inverted. When you present a credential, the reader decodes that exact structure and passes it to your access-control panel as a card number it recognises.
We build the compatible Keri Systems MS / NXT (K-Format) by encoding the identical data structure onto a programmable T5577 / EM4305 chip. Once written, the reader cannot tell the difference between our credential and the original — it presents the same bits, the same facility code, and the same card number. That is what "compatible by specification" means: not a generic look-alike, but a credential engineered to read exactly as the original does.
The Keri Systems format sits among the specialist proximity credentials most card vendors never tooled up to produce — which is why the only other source is usually the original manufacturer, at a steep premium. Supporting these hard-to-find formats is exactly what Security ID Systems specialises in. Tell us the format printed on your card, or send a sample for us to read, and we confirm compatibility before you order.
Also known as
Keri · Keri NXT · Keri MS · K-Format · ker 125khz · KC-10X · MT-10X · PKT-10X
Keri Systems and all other brand and product names are trademarks of their respective owners. Security ID Systems is an independent manufacturer and supplier of compatible access-control credentials and is not affiliated with, authorized by, sponsored by, or endorsed by these companies. Brand and format names are used only to identify the systems our products are compatible with. MIFARE and DESFire are registered trademarks of NXP B.V.