18" x 30" or 30" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter fixed bar + Product Details Size –

+ Product Details Size – 26"w X 12"h is the size for the duct opening measurement only

+ Product Details Size – 25"w X 26"h is the size for the duct opening measurement only

+ Product Details Size – 14"w X 18"h is the size for the duct opening measurement only

+ Product Details Size - 10"w X 10"h is the size for the duct opening measurement only

+ Product Details Size - 32"w X 24"h is the size for the duct opening measurement only

18" x 30" or 30" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter fixed bar + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 30" OR 30" x 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 32. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 75" x 29. 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