8" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 10.5"] 3-Way or 4-Way + Product Details Size –

+ Product Details Size – 36"w X 18"h is the size for the duct opening measurement only

If you are looking to enhance your project with a top-of-the-line unit

+ Product Details Size - 30"w X 26"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 20 5/8" width X 22 5/8" height

+ Product Details Size – 20" x 28" or 28" x 20" is the size for the duct opening measurement only

8" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 10.5" X 10.5"] 3-Way or 4-Way + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 8" x 8" duct opening (measured at the opening), with actual outer dimensions of 10. 5" W x 10. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 7. 75" x 7. 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 strong,