This round vent is made from plastic and has an adjustable centre which can be opened or set to restrict airflow.
Universal Fans Store » Vent Cone Ceiling Diffuser – Size Options
Models | 150, 200
Colours | White
SKU | EVFLCXXX
This is an inside vent used with exhaust fans. It would typically be installed on the ceiling and has an adjustable centre allowing the vent to open or restrict the level of airflow.