6 Set Pistons Rings Kit with Φ82mm bore and 11:1 compression ratio, designed for engines with model number N52B25.This kit includes six sets of piston rings engineered to fit specific engine configurations.The aluminum construction supports efficient engine , while the compression ratio is optimized for performance.The cylinder bore is precisely engineered to Φ82mm, with ring thickness set at 1.2mm for the first ring, 1.5mm for the second ring, and 2.0mm for the third ring to help reduce wear and support consistent engine function.Compatible with certain models from 2005 to 2011, including those designated as 323i, 325i, 525i, and chassis variants E60, E90, and E92.engine specifications match before installation.