At 47" it's the tallest of any certified fireplace in the industry. Wood or gas burning. The tall, clean faced, slant back design and flush to the floor platform are certainly welcome features to anybody familiar with real traditional site-built masonry fireplaces. The Citadel II features an outside combustion air supply system that directly supplies the flame via a separate, cold air flex duct. This gives the fireplace it's warm yellow flame color and lazy action, while eliminating performance problems at altitude or in difficult weather conditions.