Abstract: Apparatus contemplating a damper apparatus for controlling airflow through a ductwork in an air handling system. The damper has a stationary plenum having a collar defining a through opening. A damper blade assembly has a rigid damper blade defining a substantially flat area sized larger than a cross-sectional area of the through opening. The damper blade is selectively positionable between an open position in which the flat area is retained parallel to the collar and thereby clearingly disengages the plenum to open the through opening an thereby permit the airflow to pass through the plenum, and a closed position in which the flat area is perpendicular to the collar and engages against the collar to close the through opening and thereby prevent the airflow from passing through the plenum.