A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 6685-01-322-8386
NSN 5855-00-411-8688
NSN 5960-01-530-0581
NSN 5895-00-680-9784
NSN 5975-00-456-2257
NSN 6650-01-045-5494
NSN 2925-01-004-5627
NSN 6645-01-335-5845
NSN 5985-00-139-6025
NSN 5920-01-139-4384
NSN 5925-01-377-3480
NSN 5895-01-531-2986