Our exhaust diffusers are made of galvanized steel with white semi gloss enamel coating. To create an airtight seal, the diffusers includes a gasket and a friction-fit into duct. Adjustment of airflow is simple, just rotate the inner cone to the required setting and lock it in position with the single nut. Available in 4”, 5”, 6” & 8" sizes. Includes separate mounting collar for easy detachment.