Installing replacement mixer
The taps or mixers are mounted on the sink or sink using a threaded ring.
Close the main water tap, unscrew the hoses connecting to the cold and hot water system.
Unscrew the fixing ring at the sink.
Replace the mixer and refit.
The tap on the faucet operates a gasket that closes and opens the pipe by passing or not passing the water flow.
Single-lever mixers instead mix cold and hot water through ceramic "gaskets" with progressive holes from fully open to closed.