18" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w12h12 + Product Details Perfect Fit

+ Product Details Perfect Fit & Easy Sizing - Designed for a 16" x 16" duct opening (measured at the opening)

+ Product Details Size - 14"w X 8"h is the size for the duct opening measurement only

+ Product Details Size - 25"w X 4"h is the size for the duct opening measurement only

+ Product Details Size – 24"w X 8"h is the size for the duct opening measurement only

18" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w12h12 + Product Details Perfect Fit+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 20. 75" x 20. 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