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 – 20"w X 20"h is the size for the duct opening measurement only

+ Product Details Size – 12" x 20" or 20" x 12" 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)

3/8" - 4223 PSI

Solid Base Construction – Features a solid base for stable installation and reliable protection

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