Comparison : Item # 818B, Aluminum 918 Series Dual Point Drop Elbow
Item # 818-300A, Aluminum 918 Series Dual Point Drop Elbow with Outlet AF-300
Item # 818-400A, Aluminum 918 Series Dual Point Drop Elbow with Outlet AF-400
Item # 818FG, Flat Fiber Gasket
Item # 818G, Polyurethane V Type Gasket