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 are featured with the latest LED technology. These cluster lights have 8 functions from steady-on to an array of twinkle and fading functions. They can be used indoors or outdoors. Cluster Lights won’t tangle, no more struggling to get your lights ready to use. The long lasting LED bulbs are virtually unbreakable. Bulb life is approximately 50,000 hours. Always cool to the touch. Includes 13-foot lead wire. UL (Underwriter's Laboratories) approved transformer.