CRC Maniseal Exhaust Cement seals and bridges gaps and imperfections in exhaust clamping areas (at the manifold, the manifold flange and gasket, and ends of the muffler) and is safe to use on all exhaust systems. When heated, this Exhaust Cement expands and sets, which ensures a perfect seal against noxious fumes such as carbon monoxide. Ability to withstand high temperatures up to 300°C