Specification :

LED Penlight LED Penlight lasts up to sixteen hours on fresh batteries. Features: Bright lifetime LED light. Durable aluminum body stands up to falls and rough handling. Small enough to fit in your pocket.
the LED penlight is actually much more efficient at using the power in the batteries than is the incandescent competition. The Energizer LED penlight hits 50% starting output in 3½ hours, while the Eveready incandescent light hits 50% starting output in just 30 minutes. Not only that but after 3½ hours, at 50% output, the LED penlight is still producing MORE light than the incandescent penlight was producing when it was FIRST TURNED ON with new batteries! Nice!