20" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Return Grille + Product Details Perfect Fit

+ Product Details Perfect Fit & Easy Sizing - Designed for a 10" x 10" duct opening (measured at the opening)

+ Product Details Size - 18"w X 30"h is the size for the duct opening measurement only

Actual Filter Size – 27 3/4"w x 15 3/4" x 1"

+ Product Details Size - 4" Diameter is the size for the duct opening measurement only

actual front end outer dimensions are approximately 16 5/8" width X 34 5/8" height

20" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Return Grille + Product Details Perfect Fit+ Product Details Perfect Fit & Easy Sizing Designed for a 20" x 18" OR 18" x 20" duct opening (measured at the opening), with actual outer dimensions of 22. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 19. 75" x 17. 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