A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5945-01-593-1912
NSN 6220-01-648-3578
NSN 4140-01-198-9990
NSN 5998-01-148-4969
NSN 5960-01-530-0581
NSN 6620-00-988-0976
NSN 6610-01-156-0810
NSN 5935-00-454-3188
NSN 6150-01-302-9663
NSN 7035-00-476-7178
NSN 5945-00-756-0455
NSN 5905-01-499-0044