12" X18" Heavy Gauge Steel Floor Grille Heavy Gauge Floor Grill (no air flow control) - Brown Color (slightly reddish hue) For 12" x 18" opening in the floor with an overall size 13 13/16" x 19 13/16" These heavy gauge grills will hold up to 300 pounds 75% free air flow spacing ensuring enough air flow for your system Constructed of 100% steel for unbeatable durability