4 Inch Round Roof Rain Cap HVAC Vent Galvanized Steel All Weather Chimney Cap Roof Top Round Roof Vent with Rubber Gasket for Perfect Insulation Vent Cover (4'' Inch) - - Amazon.com
Active Ventilation 8 in. Dia. Aluminum Vent Pipe Cap in Mill Finish VPC-8 - The Home Depot
Active Ventilation 10 in. Dia Aura PVC Vent Cap Exhaust with Adapter for Schedule 40 or Schedule 80 PVC Pipe in Mill Finish AV-10-PVC - The Home Depot
3-7/8" Air Vent Grommet Cap - Classic Round Plastic Grommets Flip-Top® Tab - Mockett