A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6150-01-548-4309
NSN 5945-00-201-1224
NSN 6145-00-553-8196
NSN 6320-01-547-2743
NSN 5950-00-145-9781
NSN 6145-00-218-7831
NSN 5945-00-770-2545
NSN 5835-01-657-0245
NSN 6150-00-241-2184
NSN 5990-01-334-4111
NSN 4140-01-253-5237
NSN 5985-00-392-8078