18" x 28" or 28" x 18" Cube Core Eggcrate Return Air Grille white and sound level range of

and sound level range of NC 25 to 35

please note that the total outer dimensions of the grille measure 7" in diameter

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

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 and sound level range of+ 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