Thank you for your question. The button on top of the cartridge is a handle limit stop. This faucet includes an integrated handle limit stop that has two positions.
When you position the button to the left, this position allows full handle motion (the full range between “all cold” to “all hot”). The faucet is set in this position in the factory. When you position the button to the right, this position allows half of the normal handle motion (“all cold” to “mixed hot/cold”).
The handle limit stop can be adjusted by the homeowner once the faucet
is installed. Setting the handle limit stop in the second position may help to prevent scalding because it limits the amount of hot water in the mix.
To change positions of the handle limit stop: remove the handle;
move the valve stem to the all cold position so the water is on; change
the position of the handle limit stop; turn off the water; reinstall
Date published: 2017-12-02