2. 20 1 stainless steel generally refers to 20 1 stainless steel and acid-resistant steel, which belongs to high manganese and low nickel stainless steel with low nickel content and poor corrosion resistance. 20 1 is also commonly known as "industrial high manganese steel". If such steel is used to make water cups, people will easily cause cancer after long-term contact with materials with high manganese content and drinking them for a long time. Children's long-term use of such water cups will affect brain development and inhibit physical growth. Severe cases can immediately induce lesions, and such examples have happened many times. Therefore, 20 1 stainless steel must not be used as the production material of stainless steel water cups.