The disc with code 11.01299-0138.0 is a key mechanical element in the MAN L21/31 engine, typically used in rotational or sealing assemblies. Its precise machining and material strength allow it to maintain alignment, absorb stress, or serve as a spacer or retainer depending on its location within the engine. This seemingly simple part contributes to overall engine balance, durability, and vibration control, particularly in high-speed and high-pressure operational environments.