Necklaces that glow are a go! Did you know glow was the first to show how to market light up products at night? Nice! Non-toxic fun for everyone. Parties in the park break out some Necklaces and give them a crack. Before you know it, you've got a glow in the dark rave with activated favors everywhere. Eight hours later make sure to dispose properly since these obviously don't use batteries. 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. This will release the chemical from within the glow Necklace and it will immediately start to GLOW! They will last approximately 6 - 8 hours once activated. Each Necklace is 22 inches in length and attaches using the provided connectors. - Length: 22.0 in. , 55.9 cm. Width: 0.2 in. , 0.5 cm.