18" x 28" or 28" x 18" Cube Core Eggcrate Return Air Grille w24h24 6" width X 9

6" width X 9

actual front end outer dimensions are approximately 24 5/8" width X 22 5/8" height

+ Product Details Perfect Fit & Easy Sizing - Designed for a 18" x 30" OR 30" x 18" duct opening (measured at the opening)

10"w X 3"h Is The Size For The Duct Opening Measurement Only

European: EN 10270-1-SM

18" x 28" or 28" x 18" Cube Core Eggcrate Return Air Grille w24h24 6" width X 9+ 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