28" x 14" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 12" Diameter + Product Details Size -

+ Product Details Size - 18"w X 34"h is the size for the duct opening measurement only

+ Product Details Size - 8"w X 16"h is the size for the duct opening measurement only

Actual Filter Size – 31 3/4"w x 33 3/4" x 1"

actual front end outer dimensions are approximately 12 5/8" width X 22 5/8" height -

actual front end outer dimensions are approximately 32 5/8" width X 18 5/8" height

28" x 14" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 12" Diameter + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 28" x 14" OR 14" x 28" duct opening (measured at the opening), with actual outer dimensions of 30. 5" W x 16. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 27. 75" x 13. 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