The Cometic C5609 MLX Head Gasket is a high-performance gasket that is designed for use with the 6.7 Cummins engine. This gasket is made from MLX construction, which gives it increased strength and ability to rebound. It also has multiple thicknesses to provide better sealing. The 4.312" bore size gives you increased power and performance, while the flouroelastomer rubber-based material provides superior resistance to corrosion.