20" x 28" or 28" x 20" Cube Core Eggcrate Return Air Grille w6h6 + Product Details Size -

+ Product Details Size - The listed 5" diameter refers specifically to the size of the duct opening

Actual Filter Size – 33 3/4"w x 29 3/4" x 1"

Actual Filter Size – 23 3/4"w x 25 3/4" x 1"

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 20" duct opening (measured at the opening)

20" x 28" or 28" x 20" Cube Core Eggcrate Return Air Grille w6h6 + Product Details Size -+ Product Details Size 20" x 28" or 28" x 20" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 21. 75" X 29. 75". High Quality High quality, rust free aluminum construction with smooth finished edges and counter sunk screw holes (screws included); no sharp edges.. Installation Location sidewall and ceiling. Design Cubic core eggcrate design Offers highest airflow efficiency at almost 95%, reducing