18" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Color_Aluminum + Product Details Size -

+ Product Details Size - 28"w X 6"h is the size for the duct opening measurement only

+ Product Details Size - 8"w X 34"h is the size for the duct opening measurement only

875" width X 8" height

+ Product Details Size – 10" X 2" is the size for the duct opening (floor/vent hole) measurement only

from 4" to 20"

18" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Color_Aluminum + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 6" OR 6" X 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 8. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 75" x 5. 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