10" x 36" or 36" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 38.5"] Supply Grille + Product Details Size -

+ Product Details Size - 30"w X 24"h X 2"d (for duct opening measurement only)

+ Product Details Perfect Fit & Easy Sizing - Designed for a 6" x 16" or 16" x 6" duct opening (measured at the opening)

Actual Front End Outer Dimensions Are 16" Width X 8" Height - SEE IN DESCRIPTION HOW TO MEASURE A GRILLE

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With a 5" diameter for the duct opening measurement

10" x 36" or 36" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 38.5"] Supply Grille + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 10" x 36" or 36" x 10" duct opening (measured at the opening), with actual outer dimensions of 12. 5" W x 38. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 9. 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