Comfort Flame"s 90 Degree Elbow is designed for use with Comfort Flame and FMI 5 inch x 8 inch collared direct-vent fireplaces. Features galvanized steel on the outer wall and stainless steel on the inner wall. 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.