18" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Grille Designed for both wall and

Designed for both wall and ceiling applications

rated at R3

+ Product Details Size - 36"w X 20"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 32 5/8" width X 20 5/8" height -

+ Product Details Size – 6" x 6" is the size for the duct opening measurement only

18" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Grille Designed for both wall and+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 20. 75" x 20. 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 Made from