To activate your Light Up Tube Bracelet, flip the small black switch at end of tube, wrap it around your wrist and you’re ready to go! Lights have one cool function: “chasing lights” flash. LED Color: Purple Dimensions: Roughly 3″ to 3.75″ Diameter is adustable, flexible & comfortable – one size fits most. Bracelets include 3 non-replaceable AG3 Batteries.