18" x 20" or 20" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 18" Round Duct Pipe actual front end outer dimensions

actual front end outer dimensions are approximately 14 5/8" width X 38 5/8" height -

Ring Base Design – Allows for easy installation without removing the thermostat

Versatility and Durability: The red oak wood not only adds a touch of warmth and softness to your room but can also be sanded and refinished according to your specific application needs

actual front end outer dimensions are approximately 36 5/8" width X 26 5/8" height

+ Product Details Size - 28"w X 22"h is the size for the duct opening measurement only

18" x 20" or 20" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 18" Round Duct Pipe actual front end outer dimensions+ 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