Fairy Berries String Lights feature 12 Berries spaced 12 inches apart. These 3/4-inch diameter balls produce a glowing tiny light that fades on and off slowly. Collectively, they produce a moving firefly or fairy light effect that is absolutely unique. One set of 3 x AA batteries (not included) will power up to 5 strings for many hours of magical ambiance. Each Fairy Berry on the string fades in and out independently. Attach up to five strings together.