18" x 30" or 30" x 18" Cube Core Eggcrate Return Air Grille 6" Diameter + Product Details Size -

+ Product Details Size - 26"w X 12"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 14" x 16" OR 16" X 14" duct opening (measured at the opening)

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+ Product Details Size – 12" x 18" or 18" x 12" is the size for the duct opening measurement only

With a 5" diameter for the duct opening measurement

18" x 30" or 30" x 18" Cube Core Eggcrate Return Air Grille 6" Diameter + Product Details Size -+ Product Details Size 18" x 30" or 30" x 18" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 19. 75" X 31. 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