12" x 36" or 36" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Color_White + Product Details Size –

+ Product Details Size – 30" x 36" or 36" x 30" is the size for the duct opening measurement only

this diffuser is the perfect blend of function and style for your home

+ Product Details Size - 18"w X 18"h X 2"d (for duct opening measurement only)

14"w X 8"h Is The Size For The Duct Opening Measurement Only

12" x 36" or 36" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Color_White + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 12" x 36" or 36" x 12" duct opening (measured at the opening), with actual outer dimensions of 14. 5" W x 38. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 11. 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