16" x 36" or 36" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Color_Black Ideal for Walls & Ceilings:

Ideal for Walls & Ceilings: Designed for seamless installation in standard 24" X 4" duct openings

+ Product Details Size - 32"w X 8"h is the size for the duct opening measurement only

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

+ Product Details Size - 16"w X 25"h is the size for the duct opening measurement only

designed for superior airflow control and noise-free operation

16" x 36" or 36" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Color_Black Ideal for Walls & Ceilings:+ Product Details Perfect Fit & Easy Sizing Designed for a 16" x 36" OR 36" X 16" duct opening (measured at the opening), with actual outer dimensions of 18. 5" W x 38. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 15. 75" x 35. 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