4pcs Engine Pistons Rings Set made from forged aluminum with a hard anodized finish.Designed for performance applications, these pistons are engineered to enhance engine efficiency and longevity.The set features a cylinder bore of Φ82.00mm and a compression ratio of 11:1, providing a balanced combination of power and fuel efficiency.Piston pin diameter is 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 designed to fit models including F20, F23, F33, F55, F56, G30, 120i, and 220i.Matches OEM part numbers 11258678931, 11258657760, 11258618503, and 11258638450.Constructed to meet specifications, this set serves as a direct replacement for compatible engine rebuilds and performance. This is not an part.All brand mentions are used strictly for compatibility reference.