Spectre Header Gaskets are designed using high quality materials and engineered for optimum fit and function. Made from compressed ceramic fiber (CCF) that outperforms typical non-asbestos gaskets, CCF will not deteriorate from excessive heat or pressure. Designed for 3 inch outside diameter collector flanges, these extra thick 1/8 inch gaskets will help stop header leaks, and can even conform to warped header flanges and manifolds.