The Most Popular Reusable Glow Stick - it is the perfect marker in the darkness - attach it to important gear like backpacks, dry bags, EDC bags, emergency kits. It quickly recharges by absorbing any abient light (natural or artificial), glows all night long, and lasts forever. Our reusable glow sticks never wear out or expire. You can use them over and over again! The plastic tube is filled with the brightest strontium aluminate crystals which are surrounded by a clear resin so the glow stick is virtually unbreakable. (Contains No liquids or Gels).