Tomtop Adjustable 3 Mode LED Shower Head Sprinkler Temperature Sensor RGB Color No batteries and external power supply, it will illuminate after water flows down. The sensitive shower head light will change colors according to the temperature of water. The color's change remind you the water's temperature. Water glows Red when water is Hot (temperature above 39C). Water glows Blue when water is Warm (temperature is 32C - 38C).