18" x 28" or 28" x 18" Cube Core Eggcrate Return Air Grille white Actual Filter Size – 21

Actual Filter Size – 21 3/4"w x 13 3/4" x 1"

and sound level range of NC 25 to 35

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+ Product Details Perfect Fit & Easy Sizing - Designed for a 14" x 24" OR 24" X 14" duct opening (measured at the opening)

Design – Removable door/face for easy filter change & cleaning - uses a 1" thick filter

18" x 28" or 28" x 18" Cube Core Eggcrate Return Air Grille white Actual Filter Size – 21+ Product Details Size 18" x 28" or 28" x 18" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 19. 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