12" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 14.5" X 14.5"] Aluminum + Product Details Size -

+ Product Details Size - 24"w X 18"h is the size for the duct opening measurement only

our grill boasts an impressive 96% airflow capacity

+ Product Details Size - 36"w X 20"h is the size for the duct opening measurement only

rust-free aluminum construction with smooth finished edges and counter-sunk screw holes (screws included)

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12" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 14.5" X 14.5"] Aluminum + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 12" x 12" duct opening (measured at the opening), with actual outer dimensions of 14. 5" W x 14. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 11. 75" x 11. 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 Made from