The new design flush button in the tank has split into two. Therefore it has two buttons, big and small.
These buttons or livers are attached to an exit valve.
The big button flushes a 6-litre amount of water at a time.
The smaller button rinses 3 to 4.5-litre water at once.
So they are supposed to preserve water.
According to the states, proper use of these buttons can save 20 thousand litres of water annually.
Victor Papanek was the originator of this idea.
Victor Papnak published this idea in 1976 in his book, Design For The Real World.