A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6620-01-078-6372
NSN 6320-01-129-9656
NSN 5990-01-433-3786
NSN 5950-01-040-1307
NSN 5950-01-290-3829
NSN 6145-01-609-6549
NSN 5930-00-823-7797
NSN 5925-01-351-5542
NSN 6110-01-364-8880
NSN 5996-00-433-8285
NSN 5915-00-895-0527
NSN 6240-01-606-9998