A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5990-01-623-0082
NSN 5965-01-323-0501
NSN 5985-01-643-0205
NSN 5990-00-199-0081
NSN 6645-01-318-1874
NSN 5920-01-231-3615
NSN 6220-01-586-0982
NSN 5905-01-042-4386
NSN 5985-01-172-3360
NSN 5855-00-361-0167
NSN 5999-01-085-1868
NSN 6220-01-182-1083