Insulating fire bricks are special insulation bricks with low thermal conductivity, used for hot-face linings of furnaces and kilns as well as in backup insulation applications. LBK insulating bricks are very lightweight and have low thermal conductivity. Containing 41–73% Al₂O₃, LBK insulating bricks provide excellent performance in hot-face and behind-lining applications in industrial furnaces such as:

Annealing furnaces
Galvanizing furnaces
Heat treatment furnaces
Air heating furnaces
Naphtha cracking furnaces