It's all with water, depending on which one you like. After all, Lekoule specializes in making cups. How can I put it? The heat preservation effect is much better. Locking is actually safer. After all, it is famous for making lunch boxes and cups. See which one you like, or you can use both, but it is recommended to use a glass cup, depending on the efficacy of the cup and your needs. The cup I use can be used as health water. I bought it two months ago and I like it very much!