A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5950-01-567-0235
NSN 6240-01-315-6928
NSN 5998-01-220-9452
NSN 5960-01-539-1956
NSN 6240-00-570-9884
NSN 5905-01-023-1732
NSN 5985-01-179-5864
NSN 4140-01-603-2694
NSN 6610-01-287-3678
NSN 5835-00-911-2340
NSN 6145-01-572-3865
NSN 6240-01-243-6884