Generally, we have to divide the fine nut and the coarse nut first, but in fact, no matter what fine teeth or coarse teeth, their specifications are the same. Their specifications are M3, M4, M5, M6, M8, M10, etc. . But there is also a kind of hexagonal nut with a British system and a US system. This is just a different national standard. What we produce in China is called the national standard hex nut.