34" x 20" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Width_20in + Product Details Size –

+ Product Details Size – 20" x 36" or 36" x 20" is the size for the duct opening measurement only

+ Product Details Size – 24" x 30" or 30" x 24" is the size for the duct opening measurement only

And One Towards The Bottom Of The Door

+ Product Details Size - 30"w X 34"h is the size for the duct opening measurement only

34" x 20" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Width_20in + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 34" x 20" Or 20" x 34" duct opening (measured at the opening), with actual outer dimensions of 36. 5" W x 22. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 33. 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