Material: Aluminum Design and Style: Standard 0.00 specification, not requiring cylinder expansion Cylinder Bore: 84.00mm Ring Thickness: 1st ring 1.2mm, 2nd ring 1.5mm, 3rd ring 2.0mm Compatibility: Designed for N55B30 and N55B30A 3.0L L6 (2979cc) Twinpower Turbo engines OEM Part Numbers: 11258619196, 11257610297, 11257610298, 11257589824, 11257587914 This 6-piece piston ring set is engineered for precise fitment with a standard 84.00mm bore diameter, eliminating the need for cylinder block modifications.The three-tier ring design with incremental thickness supports effective compression sealing and reduced oil consumption.Constructed from aluminum, the rings are built to endure -stress engine conditions and maintain stable performance under elevated operating temperatures. The set is compatible with vehicle platforms including F20, F21, F30, F10, X3, X4, X5, X6, E82, and E88 models equipped with the N55 engine.Matching OEM specifications integration into the engine assembly.The material composition meets thermal , with performance stability up to 105℃, supporting in demanding driving conditions. This product is an aftermarket solution.Brand names are mentioned only to clarify compatibility with specific models.