6PCS Pistons Rings STD Low Compression 9.7:1 11257561850 For E60 E90 325i 523i N52B25 Engines Pistons Rings Accessories Material: forged aluminum Compression Ratio: 9.7:1 Cylinder Bore: Φ82mm Ring Thickness: 1st 1.2mm, 2nd 1.5mm, 3rd 2.0mm Compatibility: E60 E90 325i 523i N52B25 Engines Package Contents: 6x Pistons Rings Set This pistons rings set is designed for engines with a cylinder bore of Φ82mm and features a compression ratio of 9.7:1, suitable for naturally aspirated applications.The forged aluminum construction supports durability under standard operating conditions.Ring thickness is configured with 1.2mm for the first ring, 1.5mm for the second ring, and 2.0mm for the third ring to effective sealing within the cylinder.The set is engineered as a direct replacement for OE# 11257561850 and 11257561848, allowing installation without engine modifications.It fits specific engine models produced between 2005 and 2011.The package includes six complete piston ring sets, providing all necessary components for full engine re-ringing.