A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6685-01-581-2549
NSN 6645-01-473-9179
NSN 5950-00-212-7827
NSN 5998-01-110-6039
NSN 5945-01-505-8698
NSN 6150-00-947-7658
NSN 6240-01-149-4861
NSN 6130-00-499-7717
NSN 2925-01-416-6927
NSN 6620-01-352-5640
NSN 6150-01-145-5156
NSN 5998-00-549-9243