OEM Part Number: 11 34 1 438 451 / 11341438451
33.0mm / 6mm stem
For all M54B30 and M54B25 engines.
Intake valves are not made of ordinary steel, but of martensitic steel alloys containing chrome and silicon.
These metals can be hardened thermically (=tempered) in order to strengthen the valve seat and the top of the valve stem.