JE Pistons MLS head gaskets have a unique rubber-like coating and multi layers of steel (MLS). They ensure that engine gasses can only escape via the exhaust ports, while preventing coolant and oil from leaking into the cylinders and combustion chambers. The outer layers have raised and sunken designs built into the stainless steel to provide a seal in key areas, and the inner layers act like a spring to expand and contract under high-pressure applications. MLS head gaskets are designed to maintain their seal in extreme conditions, for a stabilized gasket with less distortion and an improved combustion seal around the cylinder bores. For replacement or upgrade, order the model recommended for your specific vehicle and engine application.