The sigma nugget is designed for high traffic roads where safety is top priority it uses a 12 watt high power led and our new fresnel lens to provide more than 220 of lateral visibility since it is meant to be used every day it is powered by a usb rechargeable lithium ion batterythis powerful light provides excellent visibility up to 400 meters its small size fits perfectly on all bikes and the belt clip allows you to use it hiking walking running and more