A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5855-01-435-5548
NSN 5998-00-014-4050
NSN 5835-00-401-8655
NSN 5996-01-480-4559
NSN 6150-01-634-0575
NSN 5945-01-448-9340
NSN 5965-01-165-9787
NSN 6650-00-555-1061
NSN 5855-01-475-7061
NSN 5935-01-602-4307
NSN 7035-00-529-3128
NSN 6320-00-823-2015