The Black & Decker® LED Emergency Bulb provides safety and security with instant lighting whenever its needed. The emergency bulb turns on automatically in the event of a power outage. Users can replace their existing light bulbs with the emergency bulb in any standard medium-base socket. The emergency bulb’s built-in lithium-ion battery recharges during regular use, providing up to 4-hours of on-demand emergency lighting.
You can find more information on the The NCC, LLC website.