18" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter white + Product Details Size –

+ Product Details Size – 16" x 16" is the size for the duct opening measurement only

actual front end outer dimensions are approximately 24 5/8" width X 31 5/8" height

+ Product Details Size – 16"w X 12"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 26 5/8" width X 12 5/8" height -

75" Width X 37

18" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter white + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 8" OR 8" X 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 10. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 75" x 7. 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