8" x 18" or 18" x 8" Cube Core Eggcrate Return Air Grille 12in diameter + Product Details Size -

+ Product Details Size - 20"w X 6"h is the size for the duct opening measurement only

+ Product Details Size - 36"w X 10"h is the size for the duct opening measurement only

+ Product Details Size - 16"w X 6"h is the size for the duct opening measurement only

+ Product Details Size - 24"w X 16"h is the size for the duct opening measurement only

Solid Base Construction – Features a solid base for stable installation and reliable protection

8" x 18" or 18" x 8" Cube Core Eggcrate Return Air Grille 12in diameter + Product Details Size -+ Product Details Size 8" x 18" or 18" x 8" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 9. 75" X 19. 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