A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5999-00-256-9366
NSN 6650-01-142-3805
NSN 6145-01-585-8439
NSN 6110-01-316-8638
NSN 6105-01-170-2638
NSN 6130-01-300-2449
NSN 6645-01-044-6376
NSN 6105-00-338-7334
NSN 5975-01-373-5517
NSN 5855-01-332-3011
NSN 5925-01-486-3185
NSN 5905-01-039-0223