The six high reversing mill is difficult to roll thin gauge products due to the large diameter of the work roll, and it is difficult to gain advantages in the increasingly fierce market competition because the work roll, backup roll and memorial archway are very large, resulting in high production and operation costs. Due to the small working roll diameter, the multi roll machine has significantly better rolling performance than the four or six roll machine in ultra-thin specifications and difficult to deform metal products, and has a significant energy-saving effect. The twenty high rolling mill has gained market recognition for its unique advantages in rolling stainless steel, silicon steel, high-strength metal and alloy thin strips, and ultra-thin strips with stable product quality and lower operating costs.