To operate you simply press timer only once. The lights will light up automatically 8 hours a day, every day at the same time. This set also includes 8 different lighting functions! All lighting sets feature the latest LED technology. These icicle lights have 8 functions from steady-on to an array of twinkle and fading functions. They can be used indoors or outdoors. LED bulbs are virtually unbreakable. Bulb life is approximately 50,000 hours. Always cool to the touch. Includes 10-foot lead wire. UL (Underwriter's Laboratories) approved transformer. Ideal for hanging on eaves, fences, walls.