A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5905-01-573-6752
NSN 5999-00-455-4858
NSN 7035-00-523-7492
NSN 5910-01-168-6743
NSN 5905-01-385-1623
NSN 5975-01-486-9999
NSN 5965-01-396-7508
NSN 6650-01-090-0719
NSN 6130-00-216-7376
NSN 6150-01-206-1927
NSN 5855-00-125-0780
NSN 5935-01-391-6100