8" x 20" or 20" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 22.5"] 10" Round Duct Pipe these heavy-duty louvers are ideal

these heavy-duty louvers are ideal for use in attics

at predicted low air motion 35 fpm in the zone of occupancy

+ Product Details Outer dimensions: 15

The ring base allows installation without removing the thermostat

actual front end outer dimensions are approximately 28 5/8" width X 32 5/8" height

8" x 20" or 20" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 22.5"] 10" Round Duct Pipe these heavy-duty louvers are ideal+ Product Details Perfect Fit & Easy Sizing Designed for a 8" x 20" or 20" x 8" duct opening (measured at the opening), with actual outer dimensions of 10. 5" W x 22. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 7. 75" x 19. 75" x 1" Premium Airflow Efficiency High performance cube core eggcrate design allows 95% airflow efficiency, reducing energy costs and maximizing HVAC system lifespan. Durable, Rust Free Aluminum