The 43" Pre-cast Masonry Firebox Kit - Wood Burning will bring the family together for a night around the fire. Pre-cast from modular concrete at half the cost, this firebox is not only lighter, but also up to 70% stronger than the competition, with a refractory strength of 3500 PSI. This unit transforms your hearth from a basic metal firebox to an artistic stonework creation, and because it weighs less than traditional brick fireplaces, it can be installed on any floor of the home without the need for additional reinforcement. The base is pre-drilled to make rebar installation a breeze, and the 50-pound bucket of dry mortar that comes with the kit has everything you'll need to finish the job. The entire firebox can be completed in less than two hours, as opposed to a standard installation that can take up to three weeks. The knock-out is easily mortared off with the provided concrete plug for those who wish to retain their fireplace wood burning only. For those who want the convenience of a propane or natural gas fuel line, no on-site drilling will be required. Although glass doors are compatible with this firebox, they should not be left closed when a fire is burning. Additional downdraft and fire safety can also be achieved with the use of spark arrestors and chimney caps. The unit is pre-assembled and ready to use, with a fuel line knock-out you can place on either side of the firebox. Please refer to the PDF charts supplied for all relevant measurements. All elements and components are proudly made and distributed in the United States, and they meet UL 127 and UL 103 chimney standards. This firebox is ICC-ES listed. Features:|Complies with UL 127 and UL 103 chimney component standards| Approved for multi-story combustible wood floor installation |Made in the USA |Compatible with both indoor and outdoor construction| Wood burning.