So, why aluminum layered exhaust gaskets? These are the perfect solution when you have imperfections on your mating surfaces. The soft aluminum layers compress up to 50% to fill gaps in distorted/warped header and exhaust manifold flanges. You can expect easy installation with slotted mounting bolt holes. Mr. Gasket's exclusive mounting bolt tolerance locates the gasket to the cylinder head ports for exact gasket placement with no adjustment necessary. This is possible because our gaskets are engineered in such a way that the smaller tolerance denies movement out of exact placement. Our gaskets are reusable and will seal the header/exhaust - manifold/collector for the lifetime of the engine.