28" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 6" Round Duct Pipe Ideal for Walls & Ceilings:

Ideal for Walls & Ceilings: Designed for seamless installation in standard 8" X 6" duct openings

+ Product Details Size - 36"w X 8"h is the size for the duct opening measurement only

actual front end outer dimensions are 26

This aluminum adjustable louvered garage vent allows air ventilation and circulation in your garage 24 hours a day

and the second number represents the height

28" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 6" Round Duct Pipe Ideal for Walls & Ceilings:+ Product Details Perfect Fit & Easy Sizing Designed for a 28" x 24" OR 24" x 28" duct opening (measured at the opening), with actual outer dimensions of 30. 5" W x 26. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 27. 75" x 23. 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