The Kingsman ZVF33 Vent Free Zero Clearance Gas Fireplace can transform your living room into a warm, inviting setting. During the cooler winter months, this vent-free unit will keep your house and family warm. Choose from grill (louver) kits, an optional firebrick, and surround with doors to create your own unique look for this vent-free firebox. This item is simple to install and will quickly transform a room because it does not require a chimney system. This unit is 99.9 percent efficient, burning room air and expelling it back into the room. The oxygen depletion sensor pilot system on the vent-free burner system shuts down the burner system if the oxygen level in the room falls below acceptable levels.