A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6650-01-421-3850
NSN 7035-01-551-3930
NSN 6320-00-228-5678
NSN 6110-00-760-6394
NSN 5998-01-634-0604
NSN 6320-01-643-0850
NSN 5975-01-624-2006
NSN 6620-01-200-8176
NSN 4140-00-415-6513
NSN 5985-01-088-8674
NSN 5915-01-146-2958
NSN 7035-01-647-0547