4" X 30" Heavy Gauge Steel Floor Grille Heavy Gauge Floor Grill (no air flow control) - Brown Color (slightly reddish hue) For 4" x 30" opening in the floor with an overall size 5 13/16" x 31 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