Monessen L48 48" Double Wall L-Series Chimney Section. Monessen is a company that designs a large line up of upgraded fireplaces and stoves designed to make your existing fireplace or new wood burning stove really stand out with style and exceptional style and performance. This Monessen L48 48" Double Wall L-Series Chimney Section is ideal for both wood burning stoves and fireplaces. This Double Wall Section is ideal for ventilation applications which is a key part to better heat and air in the heating system. When this section of pipe is installed correctly you can count on both safety of your home, and performance that you can rely on during all those colds days throughout the year.