A brick having a low thermal conductivity and used as a backing for the more dense refractory brick.
NSN 5855-00-237-4088
NSN 5975-01-043-3084
NSN 5910-00-981-8954
NSN 6150-01-293-3616
NSN 5999-01-487-3207
NSN 5985-00-456-3199
NSN 5998-00-155-4666
NSN 5855-00-149-0766
NSN 5905-01-632-7682
NSN 6220-00-566-2848
NSN 6320-00-468-8421
NSN 5960-00-773-2406