36" x 28" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 6" Round Duct Pipe + Product Details Size -

+ Product Details Size - 24"w X 4"h is the size for the duct opening measurement only

this thermostat guard combines dependable security with a professional and attractive appearance

+ Product Details Size - 10"w X 10"h is the size for the duct opening measurement only

+ Product Description Maximize your home’s airflow with this premium 2-way air supply grille

Actual Filter Size – 33 3/4"w x 9 3/4" x 1"

36" x 28" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 6" Round Duct Pipe + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 36" x 28" OR 28" x 36" duct opening (measured at the opening), with actual outer dimensions of 38. 5" W x 30. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 35. 75" x 27. 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