The most important accessories for fans are the shutters, protection grilles and flexible connectors. The automatic shutters opens when there is a positive pressure from the fan into the duct. When the fan is not working, the air shutter closes automatically, this prevents teh air coming in or out.Backdraught shutters can be placed into the ductwork or on the wall . Fan protection grilles are an ideal protetion cover for ventilation fans,it prevents the access to the fan. The wire fan guards are standard made of metal. Flexible connectors are used to prevent vibration transmission from fans or ventilation boxes to the air duct system .