Rigorously tested to ensure reliability and longevity, the Celestron Night Vision Red Headlamp provides up to 100 hours of continuous illumination, when set to the low brightness setting. That means you can rely on your headlamp to accompany you through countless stargazing sessions, camping trips, and outdoor adventures without worrying about running out of power. And if you do run out of juice, simply pop in fresh batteries and keep going—no need to find a power source and wait to recharge via USB.