12" x 18" or 18" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 14.5" X 20.5"] 18" Round Duct Pipe Its elegant look and fine

Its elegant look and fine finish and the natural warmth of oak wood

Actual Filter Size – 17 3/4"w x 15 3/4" x 1"

Outer Dimensions Are 17

+ Product Details Size - 28"w X 20"h is the size for the duct opening measurement only

Ideal for Walls & Ceilings: Designed for seamless installation in standard 14" X 8" duct openings

12" x 18" or 18" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 14.5" X 20.5"] 18" Round Duct Pipe Its elegant look and fine+ Product Details Perfect Fit & Easy Sizing Designed for a 12" x 18" or 18" x 12" duct opening (measured at the opening), with actual outer dimensions of 14. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 11. 75" x 17. 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