1, the material is difficult to copy. Material technology can't get what you see. Even if you see a material, it is difficult to understand its composition and manufacturing process.
2, even if it takes a lot of effort to make it, it is easy to be copied by other manufacturers without effort, and dare not do it for others.
3. The manufacturing industry is relatively backward. Up to now, China can't produce die steel, while foreign production equipment has higher requirements for raw materials, so domestic stainless steel wires can't be used.