HTS Code 6902.90
Refractory bricks, blocks, tiles and similar refractory ceramic constructional goods (excluding containing, by weight, singly or together, 50% of the elements Mg, Ca or Cr, expressed as MgO, CaO or Cr2O3, containing, by weight, 50% alumina, silica or a mixture or compound of these products and those of siliceous fossil meals or similar siliceous earths)