chemlights

A glow stick is a self-contained, short-term light-source. It consists of a translucent plastic tube containing isolated substances that, when combined, make light through chemiluminescence, so it does not require an external energy source. The light cannot be turned off and can be used only once. Glow sticks are often used for recreation, but may also be relied upon for light during military, police, fire, or emergency medical services operations. They are also used by military and police to mark "clear" areas.

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