Truaire C210VM 12X04(Duct Opening Measurements) Bar Type Supply Diffuser 12-Inch by 4-Inch Sidewall or Ceiling Air Supply Grille, White Smoothglide damper Model Size Indicates Duct Opening Measurements not Wall Opening Measurements. High quality steel components , no plastic High quality powder coated The actual face size is 13.75-inch in width and 5.75-inch in height.