26" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Powder-Coated + Product Details Size -

+ Product Details Size - 18"w X 16"h is the size for the duct opening measurement only

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

actual front end outer dimensions are approximately 27 5/8" width X 32 5/8" height

The back is completely insulated

26" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Powder-Coated + 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