The 2130 is a high visibility LED flasher 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 2130IR is submersible, it is also ideal for marking your dive team. For use with special NVG equipment.