A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6150-01-003-8940
NSN 2925-00-400-5634
NSN 5895-01-584-8662
NSN 2925-01-041-8201
NSN 5895-01-178-6402
NSN 5960-00-448-9414
NSN 6620-01-221-2643
NSN 6135-01-576-9616
NSN 5950-01-634-0677
NSN 5985-00-230-1828
NSN 6650-01-395-4096
NSN 5915-01-579-4810