This fun faucet light warns you of hot stream when it changes the color to red. The light will go from blue to red when the water hits 89 Deg. F (32 Deg. Celsius). It does have functional value, is affordable and easy to install. To me there's a little jolt of pleasure when I turn the water on and the blue light comes on. And the fun effect to the kids is undeniable, they keep playing with it and waste a great deal of water. You have to shake it some times because water stays inside of it and the light stays on when there is water inside. It looks cool, only thing is it's only in one color, if they had a multi-colored one, it would be a very good faucet. It serves as an excellent warning so you will never enter the cold or hot shower again. It doesn't last forever and you may find that its life cycle is short but it's really helpful so I have bought several ones. Highly recommended if you run a day care or have little tots around.