Due to the different requirements of customers for the surface fineness of stainless steel, 6K, 10K, 12K and so on are extended on the basis of 8K. And the larger the number, the higher the precision of the mirror. 6K refers to the coarse polished mirror plate, its effect is less than the mirror; 10K refers to the polished mirror panel, which can be comparable to ordinary mirrors; 12K refers to the ultra-fine grinding polishing mirror panel, which can meet the optical use.