Maybe some people will feel strange, how come there are cups for the blind. Everyone can try, if you close your eyes and pour water into the cup, many people would probably overfill it, because it's hard to know when the water is full. So this cup for the blind is specifically designed for this issue. There are three indicator lines on the handle of the cup, and correspondingly, there are three water level sensors inside the cup. The blind just need to press the indicator line according to the amount of water needed, then they can pour water freely. When the water reaches the desired level, it will make a sound, then stop pouring water, so there won't be any overflow situation.