20" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Grilles + Product Details Size –

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

background: #5296DD

rated at R3

+ Product Details Perfect Fit & Easy Sizing - Designed for a 6" x 6" duct opening (measured at the opening)

is fireproof and ensures efficient thermal performance

20" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Grilles + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 20" x 12" OR 12" x 20" duct opening (measured at the opening), with actual outer dimensions of 22. 5" W x 14. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 19. 75" x 11. 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