To activate your Sculpted Heart Necklace, remove pull tab & press the button on back. With each push of button, choose from many light options: flash, slow change, all lights on steady, red blink, green blink & blue blink. LED Colors: Red, Blue, Green Pendant Dimensions (W x H): 3″ x 3″ Necklace Length: 28″ Sculpted Heart Necklaces come ready to use with 3 replaceable AG3 Batteries.