26" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 18in diameter + Product Details Size -

+ Product Details Size - 34"w X 26"h is the size for the duct opening measurement only

The back is completely insulated

Crafted with top-notch quality aluminum

+ Product Details Size – 32"w X 8"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 18" x 12" OR 12" X 18" duct opening (measured at the opening)

26" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 18in diameter + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 26" x 16" OR 16" x 26" duct opening (measured at the opening), with actual outer dimensions of 28. 5" W x 18. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 25. 75" x 15. 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