A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5925-00-185-4020
NSN 6145-01-079-1475
NSN 6320-01-183-8196
NSN 6240-00-283-3553
NSN 6320-00-593-0379
NSN 5945-01-521-1869
NSN 6105-01-367-1501
NSN 5910-01-109-5249
NSN 6320-00-688-9983
NSN 6220-01-656-0928
NSN 5985-00-248-3617
NSN 6650-01-393-4152