This light contains a high powered LED that is powered by a rechargeable Li-Ion battery, and is capable of an output of 45 Lumens and an approximate 24 Meter beam distance. The light can also be switched to a lower 1 lumen mode that can remain on for over 48 hours! The compact form of the Nitecore tube is perfect for attaching to a key chain or just for keeping in your pocket. The most distinct feature of the Nitecore Tube is that it can be recharged via a common USB cable. Simply plug the keylight in to any USB outlet (laptop, desktop computer or wall mounted) and the bright indicator light will shine until fully charged. The light is powered by a built in Li-Ion battery that can keep it running in high mode for over an hour. This light wouldnt be called a Nitecore without the high quality construction that users have come to expect from Nitecore brand lights. The light has also been rated IP65 Waterproof.