Rasmussen 20" Black Alterna Ventless FireStones Double Sided - DF-AFS20-BL brings a sleek, modern look to your ventless fireplace, enhancing both sides with its deep black hue. Crafted from durable ceramic-bonded refractory material, these firestones are heat-resistant and built to last without cracking. Ideal for concealing burners, this black set complements contemporary and minimalist decor. Compatible exclusively with Rasmussen Alterna Vent-Free FireStones Burners (sold separately).