36"W X 4"H [Duct Opening] Linear Aluminum Clip-On Bar Return Air Grille [Outer Dimensions: 37.25"W x 5.25"H] Compatible With Duct 4in + Product Details Size -

+ Product Details Size - 14"w X 8"h Is The Size For The Duct Opening Measurement Only

+ Product Details Size – 20"w X 20"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 32" x 28" OR 28" x 32" duct opening (measured at the opening)

It comes with two versatile mounting base options—solid and ring—making installation simple and flexible

This grill comes in four different designs

36"W X 4"H [Duct Opening] Linear Aluminum Clip-On Bar Return Air Grille [Outer Dimensions: 37.25"W x 5.25"H] Compatible With Duct 4in + Product Details Size -+ Product Details Size 36"W X 4"H is (for duct opening measurement only); actual front end outer dimensions are 37. 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