The Pak-Lite Basic snaps to the top of a 9v battery. The two white LED bulbs provide plenty of light to walk and run by at night. When you turn the switch off, the Glow-In-The-Dark plastic cap aids in locating it for the next 6+hours. The Pak-Lite Basic comes equipped with a Golden Power 9v Standard Battery which will give you 20+ hours of light. If you need a longer burn time, simply un-snap the Pak-Lite Basic and snap it onto a Duracell Alkaline or an Ultralife Lithium 9v battery (extra batteries sold separately).