Brizo T75535-NKLHP Litze Luxe Nickel TempAssure Thermostatic Valve with 3-Function Diverter Trim - Less Handles MO_YGQP1EUE

The top, smaller handle controls temperature, while the bottom, larger dial controls the water volume (flow rate). The distinct advantage to this is that you can set the temperature control to a temperature you like, and then leave it, turning the shower on and off each time with the volume control. You'll never have to fuss with the temperature again. This technology makes sure your family doesn't experience a sudden and possibly unsafe change in water temperature as a result of running water elsewhere, such as using a dishwasher, flushing a toilet or running a washing machine.