When guests encounter the Superior DRT40ST Direct Vent See-Through Gas Fireplace, they'll question if they can truly see through it. They certainly can. This fireplace may be viewed from both sides! There are no limits to what you can do. The Superior DRT40ST Direct Vent See-Through Gas Fireplace comes in a 40" see-through option with a BTU output of up to 37,000. It can be set up to run on natural gas or liquid propane. High heating efficiency and a black-painted inside for outstanding flame contrast are also included.