A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6320-01-434-6861
NSN 6145-01-478-8899
NSN 6145-01-192-2087
NSN 6110-00-660-8998
NSN 6110-01-563-3262
NSN 6320-00-098-2858
NSN 2925-01-197-7864
NSN 5920-01-488-4180
NSN 5965-01-285-7356
NSN 5915-01-321-7257
NSN 5835-00-463-6699
NSN 6105-00-498-0059