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"

+ Product Details Size – 16"w X 20"h is the size for the duct opening measurement only

Installation Location – Ceiling

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Installation of the vents will eliminate the need to raise the door ensuring security and constant air flow and reduced heat transfer into attics and adjacent house walls

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