Mr. Gasket 7421G Solid Aluminum Collector Header and Muffler Gasket Designed to prevent exhaust leakage between header and collector flanges Manufactured from high quality material Features a 3-Inch inch diameter bolt hole Highly durable Facilitates hassle free installation Designed to prevent exhaust leakage between header and collector flanges Manufactured from high quality material Features a 2.5 inch diameter bolt hole Highly durable Facilitates hassle free installation