Modelo RSV Gravedad tipo Spun to be used on intake or relief applications. Attractive low silhouette design harmonizes with modern building design. The weather protecting dampers open automatically when the fan is started. The high velocity exhaust airstream holds the dampers open preventing the entrance of rain or snow. When the motor power is cut, the dampers close to provide a complete weather seal. A rain runoff trough is located below the damper shafts to provide drainage to the outside resulting in weather-tight construction.