The 2130 is a hi-visibility LED light that can be seen over half a mile away. Just twist to turn on. It is perfect for night-time bicyclists and joggers. It is powered by 2 L1154 1.2V alkaline coin cells that last over 100 hours before replacing. Because the Mini Flasher 2130 is submersible to 500 feet, it is also ideal for marking your dive team. Packaged Weight: 0.5 oz.