A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6145-00-834-1304
NSN 6320-01-232-4664
NSN 5925-01-131-9776
NSN 5975-01-254-3883
NSN 6130-00-812-2357
NSN 2925-01-166-3228
NSN 6240-00-465-7096
NSN 6610-01-192-6478
NSN 6685-01-577-2819
NSN 5945-01-123-0591
NSN 5925-01-548-4918
NSN 5930-01-186-2021