Superior Fireplaces F3306 Vent-Free Fireplace Firebox with Liner, 36"These universal heat circulating vent free fireboxes combine performance, versatility and value to add the finishing touch and ambiance to any home. Standard features include multiple interior options and heat circulating smooth faced design for increased performance when using a blower. Combined with vent free gas logs, the VRT3100 series is the choice for affordable comfort without compromise. Size: 36" Has a 24" tall opening and accepts most 24"