Rutland Products 601 Rutland Castable Refractory Cement, 25-Pound Easily fix large masonry holes or cracks in your indoor or outdoor fireplace, stove, or other heating appliance Build a solid fire pit floor or mold into custom firebrick shapes, the possibilities are endless No heat cure required making your project much easier 25 pounds will cast a 12" x 12" x 3" block For interior or exterior use, rated to 2,200 Degrees F (1,200 Degrees C)