16"W X 16"H [Duct Opening] 4-Way Aluminum Curved Blade Adjustable Air Supply HVAC Diffuser [Outer Dimensions: 17.75"W X 17.75"H] Aluminum Adjustable Curved Blade + Product Details Size –

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

Actual Filter Size – 11 3/4"w x 19 3/4" x 1"

The process is intuitive: simply select the appropriate ceiling square for your grill

Efficient Airflow Design: The slots are meticulously angled to diversify airflow in two directions

actual front end outer dimensions are approximately 30 5/8" width X 22 5/8" height

16"W X 16"H [Duct Opening] 4-Way Aluminum Curved Blade Adjustable Air Supply HVAC Diffuser [Outer Dimensions: 17.75"W X 17.75"H] Aluminum Adjustable Curved Blade + Product Details Size –+ Product Details Size 16"w X 16"h is the size for the duct opening measurement only, actual front end outer dimensions are 17. 75" width X 17. 75" height. Design Individually adjusting curved blades for better air flow control. Screws Included High Quality Aluminum The premium durable aluminum will never rust and it will never wear through leaving the material with an elegant, beautiful, and smooth surface, adds a luxurious touch to any home.