The WATERSAVER replaces the aerator on any faucet. Once installed the water is left on (preset to the temperature you desire). Pressure against the rod causes the water to flow, remove the pressure and the water instantly stops. You can even push the rod up and turn it 1/4th turn to make the water stay on (without holding pressure against the rod) for filling sinks, etc. It is no longer necessary to turn faucet handles, except when you need to change the water flow or temperature. In addition to providing easy access, the WATERSAVER eliminates wasted water, overflowing gray water tanks and stops dripping faucets.