12" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter sidewall The 1/2" black insulation

The 1/2" black insulation

+ Product Details Size - 28"w X 36"h is the size for the duct opening measurement only

Installation is hassle-free

+ Product Details Size - 10"w X 20"h is the size for the duct opening measurement only

12" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter sidewall The 1/2" black insulation+ Product Details Perfect Fit & Easy Sizing Designed for a 12" x 24" or 24" x 12" duct opening (measured at the opening), with actual outer dimensions of 14. 5" W x 26. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 11. 75" x 23. 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