18" x 20" or 20" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter sidewall + Product Details Size -

+ Product Details Size - 4"w X 34"h is the size for the duct opening measurement only

10" Circular Round Aluminum HVAC Supply Grille Air Diffuser - With Butterfly Damper - Vent Duct Cover

actual front end outer dimensions are approximately 36 5/8" width X 10 5/8" height

Universal Fit – Measures 6" wide x 3-1-13/16" high x 3-1/8" deep

18" x 20" or 20" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter sidewall + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 20" OR 20" x 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 22. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 75" x 19. 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