Engine Overhaul Pistons Seals Kit with Bearings and Head Bolt – Compatible With 325i, 525i, Z4, E90, E89, N52B25 engine.Includes Pistons & Rings (OE# 11257612982, 11257561848, 11257561844, 11257542057, 40407600 / 40444600), Main and Connecting Rod Bearings (OE# 11247576714, 11247628034, 11247576715, 11247576717, 11247628035, 11247552063, 11217627037, 11217581009, 11217627031, 11217627027, 11217627033), Seals and Gasket Kit (OE# 11127555310, 11127555311, 11137548031, 11127581215, 11340032582, 11340034068, 11127548799, 6135535007, 138669001, 537289015, 12270545840, 534310), and Head Bolt set.Pistons are standard size with cylinder bore diameter Φ82.00 mm, wrist pin diameter Φ20 mm, wrist pin length 46 mm, ring thicknesses 1.2 mm (first), 1.5 mm (second), and 2.0 mm (third), and compression ratio 11:1.Designed to fit the N52B25 2.5 L6 (2497 cc) naturally aspirated engine.