A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5990-01-411-5930
NSN 6645-01-633-1852
NSN 5910-00-597-5824
NSN 6610-00-008-6470
NSN 6105-00-399-1352
NSN 5930-01-480-5596
NSN 2925-01-633-4048
NSN 5998-01-474-4298
NSN 7035-01-289-0684
NSN 5998-01-380-7483
NSN 7035-01-113-6492
NSN 2925-00-483-9357