16" x 36" or 36" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Black + Product Details Size –

+ Product Details Size – 22"w X 8"h is the size for the duct opening measurement only

Actual Filter Size – 35 3/4"w x 27 3/4" x 1"

+ Product Details Perfect Fit & Easy Sizing - Designed for a 28" x 30" OR 30" x 28" duct opening (measured at the opening)

This versatile diffuser is available in 1-way

+ Product Details Size – 30"w X 8"h is the size for the duct opening measurement only

16" x 36" or 36" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Black + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 16" x 36" OR 36" X 16" duct opening (measured at the opening), with actual outer dimensions of 18. 5" W x 38. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 15. 75" x 35. 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