Used to seal inner pipe of direct vent appliances to seal fireboxes and pellet stove venting. Will resist the effects of the acidic accumulation, providing an integral seal that will thermal cycle within the fastened joint for the intended lifespan of the appliance. Comprised of high temperature elemental fibers and ceramic fillers that are encapsulated in a high temperature organic based resin. Maximum operating temperature 1050 deg. F. (565 deg. C.) Gray 10.3 oz. cartridge.