2. Water cups suitable for gyms: silicone water cups. The first recommended one is non-toxic silicone water cups, which can be said to be relatively convenient to carry. Silica gel cups are generally made of soft silica gel. When filled with water, the whole cup is upright, but when it is not filled with water, it can be folded and put into a backpack, which is also very light to pick up, and the silica gel cups are also resistant to high temperature, so it is relatively convenient to carry and use.