I have a few 10 year old 1.6 gallon per flush kohler toilets in my house that I wanted to up the efficiency on. While there is always the old “brick in the tank” method I wanted to do something that was more intelligent and gave me options based on whether liquids or solids were being flushed. I opted for a kit at Amazon that does just that. It was easy to install and has 2 push buttons, the top flushes with about 1/2 a gallon and the bottom button, which is for solids, uses about 1 gallon per flush.
Installing it is a snap. First, make sure you have a 10-Inch height clearance to accommodate the height of the new flush system. Then remove your old tanks flapper and flushing handle. You will likely need a pair of pliers to get the handle off, mine was difficult due to hard water deposits.
To install it just slide the new unit onto the overflow pipe and set it down on to the opening where the flapper used to be, taking care to make sure the new rubber properly seals. Then connect the new dual button flush where the old hand used to be and tighten the nut. Once that is donet attach the line to the back of flush button while pushing in the side blue button to lock it onto the back of the flush button.
Make sure the water level in the toilet is high or the low volume flush may not work properly.