Air Flow Drainable Blade Louvers are top performers with outstanding resistance to water penetration. The drainable blade models are the most effective louvers in minimizing water penetration through wall openings. Air Flows Extruded Aluminum Drainable louvers are high performance louvers designed to minimize water penetration through wall openings with drainable blades or dual drainable blades. Extruded Aluminum Drainable blades are available with visible or concealed vertical mullions in 2, 4 and 6-inch frame depths. Combination louvers combine the aesthetic appearance of stationary louvers with positive airflow shutoff capabilities. Drainable models provide excellent water penetration protection at high velocities.