16" x 18" or 18" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Fixed Blades Some of the best features

Some of the best features aren't readily apparent

actual front end outer dimensions are approximately 18 5/8" width X 28 5/8" height

+ Product Spec Sheet Return Air Grille Spec Sheet

+ Product Details Size – 10"w X 16"h is the size for the duct opening measurement only

+ Product Spec Sheet Aluminum Return Grille Spec Sheet

16" x 18" or 18" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Fixed Blades Some of the best features+ Product Details Perfect Fit & Easy Sizing Designed for a 16" x 18" OR 18" X 16" duct opening (measured at the opening), with actual outer dimensions of 18. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 15. 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