Floating Notes / assistant for the blind

When pour water to the cup, blinds usually need to put a finger into the cup to feel whether It is full.
Now, the Floating Note will solve this problem in a quite simple way.
Floating Note, which is made of a floating ball and the handle, help blinds to judge the water level by the levitating force. Hung the floating ball inside the edge of the cup and put a finger upon the handle lightly. When the water level is up to the very position, the floating ball will be pushed up by the levitating force, and also the finger can feel it. Then blinds are able to know the cup is full.