A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6685-01-226-0696
NSN 6650-00-266-6808
NSN 4140-01-342-4703
NSN 5935-01-140-6590
NSN 5998-01-066-3700
NSN 6645-01-333-5810
NSN 5930-01-502-4584
NSN 5910-01-364-1641
NSN 6610-01-461-8180
NSN 2925-01-624-5647
NSN 5905-00-146-0078
NSN 5930-01-237-9081