A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5950-01-215-0610
NSN 5930-01-335-4989
NSN 4140-01-406-2993
NSN 6645-00-854-2279
NSN 6145-01-605-3228
NSN 5996-00-153-0268
NSN 5998-01-068-1087
NSN 6110-01-414-0661
NSN 5950-01-577-0001
NSN 7035-00-442-1869
NSN 6135-01-603-2835
NSN 5945-01-079-9599