16" x 28" or 28" x 16" Cube Core Eggcrate Return Air Grille Insulated Line Set Actual Filter Size – 33

Actual Filter Size – 33 3/4"w x 35 3/4" x 1"

+ 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 10" x 12" or 12" x 10" duct opening (measured at the opening)

Actual Filter Size – 35 3/4"w x 33 3/4" x 1"

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

16" x 28" or 28" x 16" Cube Core Eggcrate Return Air Grille Insulated Line Set Actual Filter Size – 33+ Product Details Size 16" x 28" or 28" x 16" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 17. 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