A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6135-00-715-4001
NSN 6685-01-470-6827
NSN 6110-01-433-4457
NSN 6130-00-481-5993
NSN 6130-01-634-0603
NSN 5996-00-472-2506
NSN 6135-00-027-3914
NSN 6110-01-366-6749
NSN 2925-01-364-7926
NSN 5915-01-245-9694
NSN 5920-01-181-6369
NSN 5996-01-367-2081