24" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 12" Diameter Actual Filter Size – 24

Actual Filter Size – 24 3/4"w x 9 3/4" x 1"

+ Product Details Size - 12"w X 20"h is the size for the duct opening measurement only

Operating temperature from -40°f to +248°f [-40°c to +120°c]

Ideal for Walls & Ceilings: Designed for seamless installation in standard 16" X 6" duct openings

Actual Filter Size – 23 3/4"w x 21 3/4" x 1"

24" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 12" Diameter Actual Filter Size – 24+ Product Details Perfect Fit & Easy Sizing Designed for a 24" x 18" OR 18" x 24" duct opening (measured at the opening), with actual outer dimensions of 26. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 23. 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