Comfort Flame"s 48" Pipe is designed for use with Comfort Flame and FMI direct vent fireplaces. Use FMI 5" x 8" direct vent pipe only. Features a galvanized outer wall and stainless steel inner wall, with a patented twist lock design for easy installation. All Direct Vent and Wood Burning products require venting to the outside of the home to achieve proper ventilation and firebox combustion. FMI Products offers a full assortment of venting components to properly vent the Direct Vent or Wood Burning fireplace.