Sleeves with code EN170H13 are precision-engineered components used in the MAN L21/31 engine to provide wear protection, alignment, or sealing between moving and stationary parts. Produced from high-quality alloy steel, these sleeves offer excellent resistance to abrasion, thermal stress, and mechanical loading. By maintaining correct clearances and protecting base components from wear, they play a vital role in extending component life, ensuring smooth operation, and reducing maintenance intervals in demanding marine and industrial environments.