A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6240-01-188-7282
NSN 5855-00-361-0167
NSN 5895-01-052-4877
NSN 6685-01-012-1557
NSN 5835-01-340-7722
NSN 5895-01-089-6822
NSN 5925-01-210-7198
NSN 5835-01-158-6878
NSN 5985-01-497-9735
NSN 5965-01-302-2719
NSN 2925-01-359-9818
NSN 5950-00-871-1036