12" x 18" or 18" x 12" Cube Core Eggcrate Return Air Grille Insulated Line Set + Product Details Size – 4 X 12 Is CRFG2028 Width_14in

+ Product Details Size – 8" x 20" or 20" x 8" is the size for the duct opening measurement only

Size - 10"w X 10"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 28 5/8" width X 36 5/8" height

our product offers both aesthetic appeal and efficient airflow

Actual Filter Size – 9 3/4"w x 27 3/4" x 1"

12" x 18" or 18" x 12" Cube Core Eggcrate Return Air Grille Insulated Line Set + Product Details Size – 4 X 12 Is CRFG2028 Width_14in + Product Details Size – 8" x 20" or 20" x 8" is the size for the duct opening measurement only Size 10"w X 10"h is the size for the duct opening measurement only