Emits steady glow for 12 Hours. Glow stick is waterproof, do not use batteries. Great for emergencies, Halloween, raves, parties, camping, etc. They are used as light sources and light markers by military forces, campers, and recreational divers doing night diving. Blue cyalume 6 inch lightstick. Length: 6" (inches). California Prop 65 WARNING: This product contains a chemical known to the State of California to cause cancer, birth defects and other reproductive harm.