An emergency light is a battery-backed lighting device that switches on automatically when a building experiences a power outage. Emergency lights are standard in new commercial and high occupancy residential buildings, such as college dormitories, apartments, and hotels. Most building codes require that they be installed in older buildings as well.The Emergency Light is with built-in Long-Life and maintenance free rechargeable lead acid battery of high capacity . 14 x 5 x 6 cm - >1000 times charging and discharging recycle life Maximum lighting time 8 hrs. -Twin Tube is in advantages of energy-saving. -High light, long life and high power. -Both high light and dim light for choices.