Products Architectural Louvers, Dampers, Roof Curbs, Actuators, Grilles, Sunshades and more. Dampers - Rectangular Industrial Dampers: Model:NAH-721-1 Parallel Blade, Heavy Duty, Flanged, All Steel, Airfoil Blades, up to 20" w.g. APPLICATION The model NAH-721-1 is a heavy duty flanged frame style industrial control damper that has steel formed airfoil blades. NAH-721-1 DOCUMENTS - Submittal Sheet - NAH-721-1 BIM (REVIT) - Bearing Chart Balancing / Regulating Dampers UV Products Iris Dampers Drop Plenum Diffusers Louvers Dampers UL Listed Dampers Roof Curbs and Rails Sunshades Architectural Grilles Ventilators Doors Actuators Fans Air Measuring Products VAV Terminals Security Bars & Grilles Plenums Duct Take-Offs Custom Work Manufacturer Cross Referencing System View Now Previous Next