18" x 20" or 20" x 18" Cube Core Eggcrate Return Air Grille Color_Red Oak Wood Actual Filter Size – 15

Actual Filter Size – 15 3/4"w x 33 3/4" x 1"

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

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Actual Filter Size – 15 3/4"w x 17 3/4" x 1"

our damper helps create a well-balanced indoor environment

18" x 20" or 20" x 18" Cube Core Eggcrate Return Air Grille Color_Red Oak Wood Actual Filter Size – 15+ Product Details Size 18" x 20" or 20" x 18" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 19. 75" X 21. 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