20" x 34" or 34" x 20" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Insulated Line actual front end outer dimensions

actual front end outer dimensions are 10" diameter

these heavy-duty louvers are ideal for use in attics

And is classified as Class 1 Fire Proof - B1

+ Product Details Size - 32"w X 28"h is the size for the duct opening measurement only

20" x 34" or 34" x 20" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Insulated Line actual front end outer dimensions+ Product Details Perfect Fit & Easy Sizing Designed for a 20" x 34" OR 34" x 20" duct opening (measured at the opening), with actual outer dimensions of 22. 5" W x 36. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 19. 75" x 33. 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