This is the Konig LED shower head [HC-SH10N] When the water starts flowing the LED will light up instantly. The colour of the light will change according to the water temperature. This means you can see the temperature of the water before stepping under it! No batteries needed. • ≤32°C - green • 33~41°C - blue • 42~45°C - red • 46°C - flashing red ...Contact us if you need more help.