ThermoTight dead soft copper gasket material is .040-inch thick and seals headers or manifolds by conforming to their surfaces, Copper header gaskets are reusable, making them the perfect solution for performance engines that often see teardown, Will not turn brittle, burn up, shrink, or blow out like common paper/fiber exhaust gaskets on the market, Copper exhaust gaskets are preferred for high heat applications like turbochargers and high rpm use, Sold in pairs and compatible with standard small block Ford exhaust port applications.