A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5985-01-423-8902
NSN 5975-01-348-1984
NSN 5915-00-837-1864
NSN 6135-01-408-0313
NSN 5920-00-856-0936
NSN 5960-01-264-1906
NSN 5945-01-510-8334
NSN 6620-00-170-5296
NSN 5910-01-026-0855
NSN 5930-01-027-1022
NSN 6150-01-387-9741
NSN 5905-01-658-6264