Volume control dampers are square and rectangular type with both parallel blade operation and opposed blade operation, Low leakage blade construction, is to suit for high performance applications where dampers are subjected to face quiet, efficient, rattle free operation. VCD GB 10/20 Series is a galvanized steel high performance low leakage volume control damper, to ensure lowest resistance to airflow in HVAC systems with velocities to 2000 fpm (10.2 m/sec.) and 4” w.g. (1000Pa) may be installed vertically or horizontally (with blades running horizontally) and is rated for airflow and leakage class 2 in either direction. The standard construction is suitable for a leakage of air flow in either direction.