1 the inner design high-tech waterpower device,no need for battery ,it will light up when the water flows,and it light off immediately when the water stops ,also the colors of the led will change with the water temperature changes2 it will lights up to be green when the water temperature is less than 31 degree,light up blue when between 32 and 43 degree,light up to be red when between 44 and 50 degree ,it will be red flashing ,be careful that too hot 3 it wont lose any electric though it is waterpower .The DC current it is only around 3.5v ,the water flows and the wires system are separated.4 we have two kinds of adaptors which are suitable for most of the faucets