28" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 18" Diameter + Product Details Size –

+ Product Details Size – 10" x 36" or 36" x 10" is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 16" OR 16" x 20" duct opening (measured at the opening)

actual front end outer dimensions are approximately 27 5/8" width X 34 5/8" height

+ Product Details Size - 14"w X 10"h is the size for the duct opening measurement only

+ Product Details Size – 24"w X 30"h is the size for the duct opening measurement only

28" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 18" Diameter + Product Details Size –+ 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