To activate your Acrylic LED Star Necklace, remove the button protector & press button on back. One light function: flashing blinky. Note: This item has a face impression on it. Dimensions: Height 2.9 in. / 7.36 cm. Width 2.9 in. / 7.36 cm. Necklace 32.0 in. / 81.28 cm. LED Colors: 5 Blue Star Necklace comes ready to use with 3 replaceable CR927 Batteries.