Gravitational shutter is one of the possible elements of the outlet end point of the airspace system, which is operated by air movement caused by airflow causing the airflow (eg fan, vapor hood, etc.). When the unit in the system is operated, the formwork is open and then closes after it stops. Protects the system from external influences and possibly reverse airflow. Applicable: For a circular cross -section system with the same connection size. Frame: Plastic Saltus: Plastic