Genuine OEM BMW Ignition Immobilizer Antenna Ring, part number 61356964555. This ring-shaped antenna is mounted around the ignition switch and is crucial for the vehicle's anti-theft immobilizer system. It communicates with the transponder in the key to verify its authenticity before allowing the engine to start. A functioning antenna ring is essential for the vehicle's security and operability. Genuine OEM parts ensure correct signal reception and compatibility with the vehicle's electronic systems.