36"W X 8"H [Duct Opening] Linear Aluminum Clip-On Bar Return Air Grille [Outer Dimensions: 37.25"W x 9.25"H] Sheet Metal / Round Duct actual front end outer dimensions

actual front end outer dimensions are approximately 38 5/8" width X 12 5/8" height -

+ Product Details Size & Compatibility – The 12" round quadrant volume damper is compatible with duct 12"

It is compatible with 8" duct

40" x 16" Aluminum Spiral Duct Air Vent Grille Cover - Fully Adjustable Double Deflection HVAC Air Supply

What does this mean

36"W X 8"H [Duct Opening] Linear Aluminum Clip-On Bar Return Air Grille [Outer Dimensions: 37.25"W x 9.25"H] Sheet Metal / Round Duct actual front end outer dimensions+ Product Details Size 36"W X 8"H is (for duct opening measurement only); actual front end outer dimensions are 37. 25" Width X 9. 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