A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5965-01-099-2989
NSN 6610-01-382-7894
NSN 5895-00-300-1043
NSN 6650-00-990-7255
NSN 5930-00-277-4704
NSN 6240-01-365-5553
NSN 5965-01-362-8401
NSN 5965-00-396-3411
NSN 6240-01-370-4061
NSN 5996-01-156-4092
NSN 6145-00-546-6226
NSN 6145-01-479-6848