6" x 20" or 20" x 6" Cube Core Eggcrate Return Air Grille 12in diameter 1/2" White insulation will give

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

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

easy installation

+ Product Details Size – 32"w X 30"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 12 5/8" width X 8 5/8" height

6" x 20" or 20" x 6" Cube Core Eggcrate Return Air Grille 12in diameter 1/2" White insulation will give+ 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