16" x 18" or 18" x 16" Cube Core Eggcrate Return Air Grille Powder-Coat Actual Filter Size – 27

Actual Filter Size – 27 3/4"w x 27 3/4" x 1"

With a 4" diameter for the duct opening measurement

flex-shrink: 0

Actual Filter Size – 33 3/4"w x 31 3/4" x 1"

16" x 18" or 18" x 16" Cube Core Eggcrate Return Air Grille Powder-Coat Actual Filter Size – 27+ Product Details Size 16" x 18" or 18" x 16" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 17. 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