The practical in my opinion is especially the size. I do not wear contact lenses every day, but especially for rinsing use a saline solution. But most bottles come along with more than 300 ml. The problem: As a rule, you should throw away such an opened solution after a few a few months in order to avoid that there could possibly creep bacteria. Something can on the eye have very unpleasant consequences. Now I have mostly left still more than half at the usual bottles after this time. Quite a (money) waste so. These little bottles are against just ideal. Of course, even when traveling.