30" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w16h16 Actual Filter Size – 27

Actual Filter Size – 27 3/4"w x 35 3/4" x 1"

Ideal for Walls & Ceilings: Designed for seamless installation in standard 20" X 20" duct openings

actual front end outer dimensions are approximately 36 5/8" width X 10 5/8" height

+ Product Details Size – 22" x 24" or 24" x 22" is the size for the duct opening measurement only

actual front end outer dimensions are approximately 27 5/8" width X 22 5/8" height

30" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w16h16 Actual Filter Size – 27+ Product Details Perfect Fit & Easy Sizing Designed for a 30" x 18" OR 18" x 30" duct opening (measured at the opening), with actual outer dimensions of 32. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 29. 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