La description

RC -A
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 an  automatically;
A、When water temperature is ≤*2℃,Green color will show automatically ;   
B、When water temperature is between *3℃**1℃,Blue color will show automatically;    
C、When water temperature is between *2℃**5℃,Red color will show automatically;    
D、When water temperature is above *6℃,Red color will flash immediately.    
3. This item will change its color by detecting water temperature

RC -B
1、As the built-in device generating electricity without the battery and any other power connets to water, LED will emit the light.                
2、The light can change one color every 3 to 5 seconds so that the rainbow colors are showing gradually.