Easily find important items or objects in the dark The ArmourLite Tritium Key Ring Safety Markers offer continuous glow by utilizing Swiss tritium illumination technology. No external power source or charging-by-light is necessary to maintain the glow. The glow is completely self-powered. These handy markers can be used to easily find important items or objects in the dark. Furthermore, these markers are great for marking paths and locations. With the convenient stainless steel split key ring, you can attach the markers to keys, zipper pulls, flashlights, knives, weapons, eye glasses (requires O-rings), personal protection devices, camping lighters, and more! As an added bonus, each marker features a glass breaker on the end making it ideal for safety applications. Each unit is tested and approved for sale in the United States.