Subheading 690310: Refractory Ceramic Goods; Containing, by Weight, more than 50% of … etc.
Subheading 690320: Refractory Ceramic Goods; Containing by Weight more than 50% of … etc.
Subheading 690390: Refractory Ceramic Goods; Composition of Which N.E.C. in Heading No. … etc.