Aerovac® Model "AV 11 Series" (Opposite Blade) And "AV 22 Series" (Parallel Blade) Rectangular Volume Control Dampers (VCD) With Aerofoil Blades, Are Widely Used in Heating, Ventilation, Air Conditioning (HVAC) Systems Throughout the Middle East and South Asia. Unique Construction and Manufacturing Technique Coupled with Superior Design Make the Series AV 11 And Series AV 22 Damper Quiet and Reliable Giving Conditioned Controlled Air Volume to Various Zones with Class-I & Class-II Leakage@2000FPM & 4” W.G.