36" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter flat stamped steel + Product Details Size –

+ Product Details Size – 6" x 6" is the size for the duct opening measurement only

+ Product Details Size - 28"w X 10"h is the size for the duct opening measurement only

+ Product Details Size – 26" x 32" or 32" x 26" is the size for the duct opening measurement only

Designed for a 1" thick filter

+ Product Details Size - 6"w X 14"h is the size for the duct opening measurement only

36" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter flat stamped steel + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 36" x 16" OR 16" x 36" duct opening (measured at the opening), with actual outer dimensions of 38. 5" W x 18. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 35. 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