The bicycle lights can be installed in seconds without the need for any tools or other equipment. Add a light to your bike, backpack, helmet or other areas for maximum safety. Each of lights feature three specific modes of use-high, low and strobe-so you can be easily seen in early morning fog, dusk, nighttime, and dawn. These ultra bright LED lights feature two lithium ion batteries and offer visibility up to a half mile. This helps other riders, drivers, and walkers spot you when riding in low light or complete darkness.