A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5835-01-584-8538
NSN 5998-01-062-9549
NSN 6610-01-266-3447
NSN 5855-01-191-3404
NSN 6645-01-544-0408
NSN 5965-00-857-6622
NSN 5996-00-487-0755
NSN 6650-00-107-1667
NSN 6240-01-484-9576
NSN 5965-00-841-9195
NSN 5930-00-907-3561
NSN 5996-01-423-8452