To activate your Frosted Heart Necklace, press the button on the back of the piece and watch as the colors slowly morph from red to blue to green and back around again. LED Colors: Red, Blue, Green Dimensions: Pendant (W x H): 1.25″ x 1″ Lanyard: 22″ Frosted Heart Necklace comes ready to use with 2 replaceable CR927 Batteries.