18" x 30" or 30" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter fixed bar accordion dd { margin: 0

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+ Product Details Size – 6" x 18" or 18" x 6" 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

With a solid base for stability

+ 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 accordion dd { margin: 0+ 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