A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5965-00-888-2643
NSN 2925-01-629-9416
NSN 5965-00-492-9642
NSN 5930-01-391-5671
NSN 5935-01-538-6838
NSN 6150-00-125-9572
NSN 5965-00-170-5254
NSN 6145-00-515-6931
NSN 6320-01-512-2031
NSN 6220-01-650-0228
NSN 5999-01-449-4076
NSN 6685-01-105-7599