4pcs Engine Pistons Rings Set made from forged aluminum with a hard anodized finish.Designed for performance in select vehicle models, these pistons enhance engine efficiency and support engine longevity.The set is engineered for a cylinder bore of Φ82.00mm and features a standard compression ratio of 11:1.Piston pin diameter measures Φ22mm, with ring thicknesses of 1.2mm for the first ring, 1.5mm for the second ring, and 2.0mm for the third ring.This piston set is compatible with models including F20, F23, F33, F55, F56, G30, 120i, and 220i.It serves as a direct replacement for OEM part numbers 11258678931, 11258657760, 11259468869, 11259468871, 11258618503, and 11258638450.The design precise fitment and adherence to specifications for engine.