The Streamlight Nanolight features a 5mm White LED that is impervious to shock. It has a 100,000 hour lifetime so it will never need replacing. This light has a run time of up to 8 hours of declining usable output and machined aircraft aluminum construction with a rotating on/off head switch. Includes a non-rotating snap hook and 4 IEC-LR41 coin cells. This super-bright miniature, take anywhere with you flashlight attaches to just about anything from a key chain to a coat zipper or D-ring.