2 in. Aluminum Round Louvered Vulcan VentVulcan Vent features a honeycomb matrix with an intumescent coating that helps stop the spread of fire. This 1 piece, fire and ember resistant round louvered vent is accepted by the California State Fire Marshal and is CH 7A code compliant. Allows air to flow into attic space as part of a balanced ventilation system. The Round Louvered Vulcan Vent is made from lightweight aluminum and has a stainless steel screen. California residents see Prop 65