Rasmussen 30" Dark Gray Alterna Ventless FireStones Single Sided - AFS30-DG brings a bold, sophisticated look to your ventless fireplace with its rich dark gray hue. Made from durable ceramic-bonded refractory material, these firestones are heat-resistant, ensuring lasting quality without cracking. Perfect for concealing burners, this dark gray set complements modern and transitional decor. Exclusively compatible with Rasmussen Alterna Vent-Free FireStones Burners (sold separately).