Truaire C170 14X12(Duct Opening Measurements) Return Air Grille 14-Inch by 12-Inch Sidewall or Ceiling Return Air Grille, White Heavy gage all steel construction Model Size Indicates Duct Opening Measurements not Wall Opening Measurements. 1/2-inch spaced fins High quality powder coated The actual face size is 15.75-inch in width and 13.75-inch in height.