The Elecstor Emergency LED bulb stays on in the event of an unexpected power outage or load shedding. The emergency bulb is a direct replacement for a standard bulb, and the built-in battery will automatically charge when the bulb is switched on. With three built in dimmable settings to adjust the brightness of the light, that not only optimises the battery lifespan but also provides up to 4 hours of reliable backup lighting. If the bulb stops working for any reason, we will simply swap it for a new one. Please charge the bulbs for 10 – 12 hours for optimal use. Features: EMERGENCY LIGHT: Provides 4 hours of automatic background lighting during a power outage. RECHARGEABLE BATTERY: Lithium-ion battery built into the light bulb automatically charges when light is turned on. INTELLIGENT LIGHT OUTPUT: Maximum brightness during normal operation, automatically reduces brightness during a power outage to prolong battery life ENERGY SAVING: LED light bulb saves up to 80% energy compared to the traditional incandescent light bulb