Genuine OEM BMW high-power spark plug, part number 12120037663. This component ignites the air-fuel mixture within the engine cylinders to initiate combustion. It is a critical part of the ignition system. The plug is engineered with specific heat ranges and electrode materials to match the engine's requirements. Genuine OEM spark plugs are essential for maintaining the correct ignition timing, preventing engine misfires, and ensuring optimal fuel efficiency and power output.