I've been using these for years, I use these and larger Calum signature headlights for all sorts of things, get creative, activate and trim the greens, rub your body and run like a hulk at night, imagine being exposed to his toxic waste. Use for outdoor recreation, use indoor for emergencies or for fun. A small stick is good for marking the trail at night, large sticks eliminate a large dark area, I find green is best for lighting purposes and for the glow time, I often go off-road with friends in the woods and to mark our trails, that we nail or tie to trees to find a safe way back. Their large green and white canes are clearly visible from 500 meters away. We occasionally use them for night fishing with our gear to attract fish when permitted by law. Normally I get 12 hours of bright light, which means that during this time you can clearly light a normal bedroom or office in your home, it slowly gets darker and by 18 hours it's quite dark. I have hundreds of these - the expiration date is forever, I have 25 year old ones that I use and they work just like new ones.