A: These bricks are used as a heat barrier inside the firebox.
A: Hit retainer
A: You can use a high temp RTV silicone to secure the bricks!
A: We can't speak to the safety of the construction you intend to use this for. These bricks are rated as firebricks to withstand a max temperature of 2000°F.
A: They measure 9" x 4.5" x 1.25".