Vogelzang Wood Stove Firebrick (9" x 2.5" x 1.25") For (TR002 & VG1120): 23783. Firebricks help insulate the interior of the firebox from direct contact with the flame while also helping to hold heat inside the unit. If you notice largecracksin the firebrick or bricks that are starting tocrumbleor aredeteriorated, they should be replaced!