20"W X 4"H [Duct Opening] Linear Aluminum Clip-On Bar Return Air Grille [Outer Dimensions: 21.25"W x 5.25"H] Drop Ceilings / Aluminum Actual Filter Size – 13

Actual Filter Size – 13 3/4"w x 27 3/4" x 1"

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

Stay organized with nine internal pockets

Purposed with SNAP-LOCK/PUSH-OPEN technology and can be installed flush on to drywall

only measure the "hole" in the wall

20"W X 4"H [Duct Opening] Linear Aluminum Clip-On Bar Return Air Grille [Outer Dimensions: 21.25"W x 5.25"H] Drop Ceilings / Aluminum Actual Filter Size – 13+ 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