A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5855-00-477-9943
NSN 5996-00-861-1706
NSN 6130-01-359-2701
NSN 4140-01-133-1512
NSN 6320-01-237-9746
NSN 5910-00-570-7524
NSN 6150-01-293-0709
NSN 5998-00-064-2144
NSN 5915-01-325-5376
NSN 6320-01-459-6992
NSN 6685-01-441-2616
NSN 5965-00-698-0433