1、As the built-in device generating electricity without the battery and any other power connets to water, LED will emit the light.  
2、When water flows down,the LED will light instantly and automatically by the water temperature;
A. When water temperature is ≤32℃, Green color will show automatically;
B. When water temperature is between 33℃～41℃, Blue color will show automatically;
C. When water temperature is between 42℃～45℃, Red color will show automatically;
D. When water temperature is above 46℃, Red color will flash immediately; 
3. The built-in flow regulating valve can control water pressure effectively and improve the service life of motor hugely, as well as save water. Besides, the filter screen designed inside the flow regulating valve can filter the impurities in water, improve water quality and protect the motor rotor from being damaged.