A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6685-01-443-8095
NSN 6110-01-039-1151
NSN 5910-01-591-6801
NSN 6105-01-616-7941
NSN 5965-01-392-1761
NSN 6130-01-472-4288
NSN 5965-01-296-8991
NSN 5999-01-426-2984
NSN 6650-01-334-2649
NSN 5985-00-824-0500
NSN 6240-01-567-2376
NSN 6110-00-156-6468