8" x 14" or 14" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 16.5"] Brown + Product Details Size -

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

installation is a breeze

+ Product Details Perfect Fit & Easy Sizing - Designed for a 18" x 30" OR 30" x 18" duct opening (measured at the opening)

and keep the cold air out during the Winter Months

Insulation – A thick blanket of fiberglass insulation provides you with an R-Value of 4

8" x 14" or 14" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 16.5"] Brown + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 8" x 14" or 14" x 8" duct opening (measured at the opening), with actual outer dimensions of 10. 5" W x 16. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 7. 75" x 13. 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