The Siemens 6GT2890-0CA00 is a SIMATIC RF1000 card retainer — a transparent SAN plastic holder that clips onto any access control reader in the RF1000 family. It holds ISO cards and round transponders, and is designed to keep the transponder permanently positioned on the reader. The part latches onto the RF1000 reader body, so no separate mounting hardware or DIN-rail space is needed — it's a snap-on accessory for the reader itself.
Dimensions are 100 mm wide, 42 mm tall, and 15 mm deep — sized to match the RF1000 reader face. Rated for operation, storage, and transport across -25 to +55 °C, so it holds up in unconditioned indoor environments like warehouse entry gates or parking lot reader stations.
Because it's a simple molded accessory with no electronics, there's no PCN risk or firmware revision to track.