To activate your Acrylic LED Multicolor Mustache Necklace, slide the button on the battery pack for color splash light function: Automatically morphs from fast color change to flashing and back again. When turned off, plastic glass is crystal clear. LED Colors: Multicolor Rainbow Necklace Length: 32″ Pendant Dimensions (W x H): 2.5″ x 1.8″ Comes ready to use with 3 replaceable AG3 batteries.