Rutland Fireplace Mortar Cartridge, 10.3-Ounce, Gray Grey colored fireplace mortar Perfect for repairing small chips or cracked firebrick, re-pointing mortar joints between firebricks, and bonding firebricks together Sets as hard and as strong as firebrick after curing Approximate Coverage: 99 feet with 1/8" bead. Rated to 2000F (1090C)