Name your Palette: Description: The cap on a prefabricated fireplace serves the same function as that of one on a masonry fireplace as it is there to keep water and animals from entering the chimney. The storm collar ensures that any standing water on the chase top will roll away from the flue. The chase top encloses the top of your chimney chase, almost all factory installed or builder grade chase tops are galvanized steel that can and do rust out. Often times you won’t notice until you begin to see rust stains on the sides of the chase and by that point there is a possibility that more damage has occurred within the chimney system. http://www.mcpchimneyservices.com