Rasmussen 20" B/W/LG Mix Alterna Ventless FireStones Single Sided - AFS20-BX features a sophisticated blend of black, white, and light gray firestones, creating a striking and versatile look for ventless fireplaces. Made from durable ceramic-bonded refractory material, this set withstands high temperatures, providing enduring elegance without cracking. Ideal for concealing burners, these multi-tonal firestones offer a unique touch to any transitional or modern space. Exclusively compatible with Rasmussen Alterna Vent-Free FireStones Burners (sold separately).