6" x 20" or 20" x 6" Cube Core Eggcrate Return Air Grille 12in diameter Actual Filter Size – 27

Actual Filter Size – 27 3/4"w x 17 3/4" x 1"

+ Product Details Size – 12"w X 20"h is the size for the duct opening measurement only

+ Product Details Size – 16" x 18" or 18" x 16" is the size for the duct opening measurement only

Powder-coat finish

1/2" White insulation will give you a good R value of 3

6" x 20" or 20" x 6" Cube Core Eggcrate Return Air Grille 12in diameter Actual Filter Size – 27+ Product Details Size 6" x 20" or 20" x 6" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 7. 75" X 21. 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