1, stainless steel cup. The heat preservation effect is the best and it is convenient to carry. For food-grade stainless steel (such as 304 steel), chromium, manganese and other metals can be negligible.

2. Among all materials, glass is relatively the safest. Glass cups are usually made of inorganic silicates, which are fired at a high temperature of more than 600 degrees. Because of their relatively stable chemical composition, they will not produce harmful substances in the firing process. Moreover, the glass surface is smooth and easy to clean, and bacteria and dirt are not easy to breed on the cup wall.