12"W X 12"H [Duct Opening] 4-Way Aluminum Curved Blade Adjustable Air Supply HVAC Diffuser [Outer Dimensions: 13.75"W X 13.75"H] w34h34 Actual Filter Size – 19

Actual Filter Size – 19 3/4"w x 21 3/4" x 1"

+ Product Details Size - 30"w X 16"h is the size for the duct opening measurement only

Actual Filter Size – 29 3/4"w x 31 3/4" x 1"

6" x 6" - opening (vent hole - Neck Size) dimension - actual size is approx 2" wider

Actual Filter Size – 29 3/4"w x 29 3/4" x 1"

12"W X 12"H [Duct Opening] 4-Way Aluminum Curved Blade Adjustable Air Supply HVAC Diffuser [Outer Dimensions: 13.75"W X 13.75"H] w34h34 Actual Filter Size – 19+ Product Details Size 12"w X 12"h is the size for the duct opening measurement only, actual front end outer dimensions are 13. 75" width X 13. 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.