Christmas lights string by vidaXL length 20m, with 2000 led lights. They are green cable and emit cool white light, which is measured on the Kelvin scale with values from 5000K to 6800K. The tones of cool white are more blue compared to natural light. They allow you to choose between various lighting programs, depending on your mood, and can be extended by connecting them to other bulbs.. They operate with electricity.