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≤39℃, Blue color will show automatically;
B. When water temperature is above 40℃, Red color will show automatically;                                         
The outer glass of this kind of head shower has two styles:one is spure(D004-1),another is circle9d004-2),and two colours:blue and light red for you to choose from.