The commodities in this topic are instruments for special technical use in the laboratory, which can be classified as optical, photographic, film, measuring, inspection, medical or surgical instruments and precision instruments and equipment in Chapter 90. Parts and accessories of the above projects. According to its composition materials (graphite content is 5 1%), it can also be classified as l3 ceramic products. According to the note 1 (3) in Chapter 90, the commodity of this topic cannot be classified in Chapter 90, but should be classified in Chapter 69, Ceramic Products. Graphite is a refractory material. If you refer to the relevant sub-chapter of Chapter 69, it should be classified as silica fossil powder or similar silica and refractory products in Chapter 1. According to this topic, the graphite content of commodity (5 10A) is more than 50%. The title goods are classified as 6903 "Other refractory ceramic products (such as retort, crucible, etc.). ) ",and then as 6903. 1000" containing more than 50% graphite, other carbon or their mixture by weight ". Add 8 digits to get 19. So the correct answer to this question is 19 (6903.438+0000).