10" x 18" or 18" x 10" Cube Core Eggcrate Return Air Grille Grilles Measuring 3" in diameter for

Measuring 3" in diameter for the duct opening

actual front end outer dimensions are 17" Width X 17" Height

+ Product Details Size – 28"w X 6"h is the size for the duct opening measurement only

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 36" OR 36" x 20" duct opening (measured at the opening)

+ Product Details Size – 10"w X 16"h is the size for the duct opening measurement only

10" x 18" or 18" x 10" Cube Core Eggcrate Return Air Grille Grilles Measuring 3" in diameter for+ Product Details Size 10" x 18" or 18" x 10" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 11. 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