This awesome Blue LED Sound Reactive Necklace is a must have for anyone who loves to attend parties, clubs, or raves. Everyone will love your LED flashing necklace. To use the necklace start by simply moving the switch on the back to the left or right and the push the button to the right of the switch. on the left side is the strobe modes. There are 3 strobe modes which can be changed by hitting the black button next to the switch, Fast, Slow, and Always on. Move the switch all the way to the right and the necklace is now sound reactive and will flash with music or ambient sound. To turn the LED necklace off simply move the black switch to the middle.