Choose a 600 ml thermos cup, which is suitable for a moderate amount of drinking and easy to carry. If you only need to drink a small amount of drinks at ordinary times, or often need to carry a thermos cup out, the capacity of 600 ml is enough to meet the demand and it is more portable. In contrast, the 800 ml thermos cup has a larger capacity, which is suitable for occasions where drinks need to be preserved for a long time or need a lot of water. If you need to use the thermos several times a day, or if you need to keep the temperature of the beverage for a long time, the capacity of 800 ml is more practical.