Turn on the fun in your shower just by turning on the water. The LED lights will automatically light up and set the mood. They will even change colors automatically based on the water temperature. All this with no batteries, everything is self-powered by a built in dynamo that takes advantage of the water pressure to create the energy to light the bulbs. No Batteries! This high tech rain shower head powers the LED lights using a built in hidden dynamo. The lights will automatically turn on when water pressure is turned on. The lights will dim and brighten when you lower and raise the water pressure. So you can set the perfect mood, water light. Auto Temperature Detected Light Color Change! The shower head will automatically change colors according to the temperature of the water. So you always know how the water will feel on your skin just by looking at it. - When water temperature is below 113'F lights glow BLUE. - When water temperature is between 114'F - 121'F lights glow RED. - When water temperature is over 122'F lights flash RED.