A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6130-01-658-0532
NSN 6105-01-442-4343
NSN 6610-01-426-5090
NSN 5910-01-135-0392
NSN 5905-00-376-1771
NSN 5965-01-199-3318
NSN 6220-01-443-3430
NSN 5975-01-500-1307
NSN 2925-00-010-2632
NSN 5930-00-928-1619
NSN 6320-01-166-3602
NSN 6610-00-839-9186