26" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter return grille + Product Details Size –

+ Product Details Size – 20" x 36" or 36" x 20" is the size for the duct opening measurement only

+ Product Details Size - 8"w X 6"h is the size for the duct opening measurement only

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

actual front end outer dimensions are approximately 31 5/8" width X 24 5/8" height -

+ Product Details Perfect Fit & Easy Sizing - Designed for a 14" x 16" OR 16" X 14" duct opening (measured at the opening)

26" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter return grille + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 26" x 12" OR 12" x 26" duct opening (measured at the opening), with actual outer dimensions of 28. 5" W x 14. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 25. 75" x 11. 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