A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 4140-01-439-3329
NSN 6220-00-823-4588
NSN 6685-01-082-8910
NSN 5996-00-161-8376
NSN 5920-00-567-4100
NSN 6135-00-042-9255
NSN 2925-01-030-6580
NSN 6110-00-980-9292
NSN 5985-01-323-1972
NSN 5910-01-481-4199
NSN 5965-00-977-5658
NSN 5965-00-492-9642