Napoleon GVFL18N 18 Inch Vent Free Natural Gas Log Set 18 inch vent free 40,000 BTU gas log set for use with natural gas Infrared heat radiates back into the room for additional heat 50% flame/heat adjustment for maximum comfort and efficiency Complete with solid cast iron andirons & grate, large charcoal embers and 5lbs lava rock/cinders Minimum Size Fireplace Opening: 18" H x 24" W x 14" D