A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5996-00-279-5806
NSN 6220-01-217-4096
NSN 5910-00-015-0111
NSN 6135-01-452-2421
NSN 5975-00-644-4972
NSN 5975-00-290-4285
NSN 6685-01-440-8749
NSN 5999-00-644-3412
NSN 6650-01-025-8803
NSN 6650-00-007-3374
NSN 6650-00-116-7439
NSN 5999-00-530-4844