The Superior VRT4500 Ventless Firebox includes a 30" height opening in 36", 42", and 50" options and is designed to command a space with its immense size. This firebox is ideal if you want a fireplace that will immediately draw the attention of your guests. It's made to impress. When employing a ventless gas log set, the Superior VRT4500 Ventless Firebox achieves a heating efficiency of 99.9 percent. It also comes with a fully insulated firebox for better performance in colder regions, as well as a textured powder-coat finish for added durability. With this fireplace, you can't go wrong!