6pcs N52B25 Engine Pistons Rings Set with a compression ratio of 11:1 and cylinder bore of Φ82mm.This set includes 6 pistons and rings designed for 2.5L L6 naturally aspirated engines.The wrist pin diameter is Φ20mm with a length of 46mm.Ring thicknesses are 1.2mm for the first ring, 1.5mm for the second, and 2.0mm for the third.Compatible with engine models used in E81, E87, E83, E84, E90, E91, E60, and E61 chassis from 2005 to 2011, including variants such as 323i, 325i, 523i, and 525i.Designed as a direct replacement for OEM 11257612982.Engineered to support optimized compression and consistent engine function.