The Emergency Strobe is powered by a sophisticated electronic package encapsulated within a plastic dome. The powerful beacon of bright high intensity white light is visible for up to 3 miles. It flashes at the rate of 50-60 times per min. for 16 hours then will continue to flash at a diminishing rate for up to 40 hours depending on battery life and outside temperature. It easily attaches to a backpack belt or clothing by a stainless steel locking pin. Durable waterproof construction provides dependable performance. Powered by an easily replaced D cell alkaline battery (not included). Do not use lithium battery.