36" x 28" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 6" Round Duct Pipe actual front end outer dimensions

actual front end outer dimensions are approximately 18 5/8" width X 34 5/8" height

very easy to do

75"H – fits a 14" X 4" duct opening

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

36" x 28" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 6" Round Duct Pipe actual front end outer dimensions+ 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