2.5 "exhaust flange (4 screws) on a 3" V-Band Material: cast iron Allows for a simple construction of a high flow exhaust system. Appropriately selected shape of the housing allows to accelerate the exhaust gas flow. Dimensions available in the photos. Exhaust flange 2.5 "(4 screws) for 3 "V-Band Material: cast iron It allows for the simple construction of a high flow exhaust system. Appropriately selected housing shape allows for acceleration of the exhaust flow.Dimensions are on the photos. flue gas flow.Material: cast iron Dimensions available in the photos.