18" x 36" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 8" Round Duct Pipe + Product Details Size –

+ Product Details Size – 16"w X 8"h is the size for the duct opening measurement only

Its removable face allows hassle-free cleaning

actual front end outer dimensions are approximately 52 5/8" width X 22 5/8" height -

and squirrels

Plain Ends - Gives you the freedom to cut and flare at your own project needs

18" x 36" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 8" Round Duct Pipe + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 36" OR 36" x 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 38. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 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