A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5985-01-458-1629
NSN 4140-01-440-0087
NSN 5999-00-712-0073
NSN 6130-00-659-8106
NSN 6110-01-120-4887
NSN 6110-00-994-1791
NSN 5998-01-110-0760
NSN 6320-01-441-2438
NSN 5950-01-593-8557
NSN 5985-01-358-7495
NSN 6130-01-629-2916
NSN 6130-00-304-4827