What's FLOAT BALL?How it to work?

What's  FLOAT BALL?How it to work?

A valve composed of a crank arm and a float ball, which can be used to automatically control the liquid level of a water tower or pool. !
The float always floats on the water. When the water surface rises, the float also rises.
When the float rises to a certain position, the connecting rod also rises and supports the rubber piston pad to close the water source.
When the water level drops, the floating ball also drops, and at the same time connecting rod drives the piston pad to open.
Simple maintenance, flexible, and durable!