18" x 28" or 28" x 18" Cube Core Eggcrate Return Air Grille return filter + Product Details Size –

+ Product Details Size – 12"w X 6"h is the size for the duct opening measurement only

Actual Filter Size – 7 3/4"w x 17 3/4" x 1"

Box or Other Attachments Needed

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

Actual Filter Size – 35 3/4"w x 23 3/4" x 1"

18" x 28" or 28" x 18" Cube Core Eggcrate Return Air Grille return filter + Product Details Size –+ 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