This Cometic MLS Head Gasket is designed to replace BMW part numbers 11121726619, 1112172622, and 11121405106, specifically for the M50, M52, S50, S52 iron block U.S model versions of the inline 6-cylinder engines found in E34/E36 chassis. Cometic MLS Gaskets are composed of multiple layers of stainless steel, the number of layers used varying by application. These layers consist of both proprietary, high-temperature coated and uncoated stainless steel. Additional layers increase active seal height and can be used to fine-tune compression. The specialized coating used on Cometic Gaskets conforms to the surfaces of the cylinder head and engine block on the first heat cycle, creating a chemical bond. MLS Gaskets are able to prevent blow-outs in engines with high cylinder pressure because the embossed layers act as a ‘spring’ and compensate for increased head lift.  Please note, MLS head gaskets can NOT be used with motors that have O-rings or receiver grooves around the cylinder bores because they require smooth and flat surfaces to seal. The M50 and M52 engines have a bore of 84 mm and 0.070" thickness The S50 engine has a bore of 86 mm and 0.070" thickness The S52 engine has a bore of 86.4 mm with 0.070" thickness   Installation instructions: Make sure that the engine block and cylinder head surfaces are clean, flat, and free from any debris, oil, or coolant. Install the MLS gasket on the engine block and ensure that it is properly aligned. Avoid twisting or bending the gasket during installation. Place the cylinder head on top of the gasket and install the head bolts or studs in their correct positions. Follow the manufacturer's recommended torque specifications and tighten the bolts or studs in the proper sequence to ensure even clamping force across the gasket. After the initial tightening, re-torque the head bolts or studs after the engine has been started and then allowed to cool to room temperature. This will ensure that the gasket is properly seated and compressed. It is recommended to not use any additional sealant on the MLS gasket, as it is already coated with a Viton rubber sealant. Using additional sealant can hinder the performance of the gasket.