To activate your Disco Prism Ball LED Multicolor Pendant Necklace remove the pull table located underneath the prism ball, and press the button switch located on the opposite side. Dimensions: Height- 4 inches Lenght-2.5 inches Width- 2 inches Necklace-28 inches Setting: Prism ball has Multicolored effects. Multiple Modes Shines disco patterns on wall, floor, and ceiling. 2 replaceable AG13 batteries installed.