Tri Color Glow Necklaces contain a non-toxic, glow-in-the-dark chemical that illuminates once activated. – To activate, simply bend the necklace until you hear it crack. – Then shake it to really release all the glow throughout the piece. – To attach, connect each end to one another using one of the clear connectors included with each set. Dimensions: Length: 22.0 in., 55.9 cm. Width: 0.2 in., 0.5 cm. Colors: Each necklace glows Blue, Pink, and Green! Batteries are not required for this product.