A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6135-01-214-6441
NSN 6220-00-484-2536
NSN 5910-01-192-1848
NSN 6145-01-545-6348
NSN 5925-00-881-6659
NSN 5960-00-593-5603
NSN 5930-00-492-3272
NSN 5990-00-804-0678
NSN 6130-01-562-3497
NSN 6135-01-626-6325
NSN 5996-01-161-6296
NSN 4140-01-028-0350