18" x 34" or 34" x 18" Cube Core Eggcrate Return Air Grille 18in diameter each diffuser is carefully shrink-wrapped

each diffuser is carefully shrink-wrapped with a sturdy cardboard backing

actual front end outer dimensions are approximately 30 5/8" width X 24 5/8" height

Ideal for Walls & Ceilings: Designed for seamless installation in standard 18" X 18" duct openings

+ Product Details Size - 30"w X 36"h is the size for the duct opening measurement only

18" x 34" or 34" x 18" Cube Core Eggcrate Return Air Grille 18in diameter each diffuser is carefully shrink-wrapped+ Product Details Size 18" x 34" or 34" x 18" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 19. 75" X 35. 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