This piston rings set is compatible with N63B44A 4.4L V8 Twin Turbo engines (4395cc) found in select 550i, 750i, X5, F01, F02, F03, E70, and E71 models.OE reference numbers include 11257613626, 11257576475, 11257556955, 11257574822, 11257574823, and 11257617547.Specifications: compression height 32.1mm, piston length 52.6mm, wrist pin length 60mm, wrist pin diameter 22mm, cylinder bore diameter 89mm, and engine compression ratio of 11:1.Package includes one complete piston and rings set.