A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6240-00-132-5375
NSN 5998-01-381-8426
NSN 5999-01-145-5084
NSN 6220-00-896-6239
NSN 5960-01-424-0590
NSN 6685-01-446-6580
NSN 5905-01-501-6048
NSN 5930-01-507-8806
NSN 5945-01-539-2269
NSN 6110-01-271-5015
NSN 6145-01-088-8996
NSN 6110-01-031-8476