20"W X 4"H [Duct Opening] Linear Aluminum Clip-On Bar Return Air Grille [Outer Dimensions: 21.25"W x 5.25"H] Compatible with Duct 10" + Product Details Size –

+ Product Details Size – 20" x 28" or 28" x 20" is the size for the duct opening measurement only

this stick-on collar with damper efficiently facilitates the delivery and removal of air

The vent also has a bug screen to eliminate pest intrusion

+ Product Details Perfect Fit & Easy Sizing - Designed for a 28" x 8" OR 8" x 28" duct opening (measured at the opening)

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20"W X 4"H [Duct Opening] Linear Aluminum Clip-On Bar Return Air Grille [Outer Dimensions: 21.25"W x 5.25"H] Compatible with Duct 10" + Product Details Size –+ Product Details Size 20"W X 4"H is (for duct opening measurement only); actual front end outer dimensions are 21. 25" Width X 5. 25" Height. Design Designed for concealed, flush placement on your wall with a 3 8 inch space between louvers, this linear grille comes with an installation frame and clips for easy hook in assembly, ensuring a refined and seamless look. High Quality Aluminum The premium durable aluminum will never rust and it will never