Featuring an extruded aluminum frame and airfoil blades, the Model SMD-401EF smoke damper is available in sizes up to 192 in. wide by 120 in. high with a wide range of actuators in modulating or two-position operation. Model SMD-401EF is UL 555S Class I leakage certified and rated for velocities up to 3,000 fpm and pressures up to 6 in. wg for both horizontal and vertical installations.