These angled dampers are designed to be installed on the back of spiral duct grilles as above, and are used to regulate and balance airflow. Adjustment is made by way of a sliding gate located inside the damper body. Clips to fix the damper to the grille are included. Match damper size to SGR1 grille size i.e. 625x125 damper to a 625x125 spiral duct grille.