To activate the shining stars simply push in the knob located on the white plastic piece on the necklace. The Patriotic Star String LightsNecklace does not have a clasp to open, slip over head to wear or remove. Dimensions: Length: 35 in. , 88.90 cm. LED Colors: 2 White, 2 Red, 2 Blue Batteries: Includes 3 AG10 Batteries. Batteries for this item are replaceable.