A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5925-01-067-2928
NSN 6610-01-216-5594
NSN 6150-00-802-8362
NSN 5998-01-433-2308
NSN 5985-01-278-0493
NSN 5950-01-062-0643
NSN 4140-01-152-6600
NSN 5910-00-288-5979
NSN 7035-00-922-5700
NSN 5910-00-324-7125
NSN 5996-01-544-0135
NSN 5975-00-800-3178