22" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w8h8 + Product Details Size -

+ Product Details Size - 24"w X 36"h is the size for the duct opening measurement only

but still very thin

actual front end outer dimensions are approximately 22 5/8" width X 18 5/8" height

+ Product Details Size – 12" x 16" or 16" x 12" is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 18" x 36" OR 36" x 18" duct opening (measured at the opening)

22" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w8h8 + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 22" x 16" OR 16" x 22" duct opening (measured at the opening), with actual outer dimensions of 24. 5" W x 18. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 21. 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