The MPI Flasher Marker System is a powerful 5 L.E.D. lighting system that has 6 separately controlled flashing functions. You can have it light the trail around you with a constant "on" position of all the five lights, making it operate just like a flashlight. It will provide plenty of illumination in your immediate area. You can also select to just have all the lights flash in a slow speed, this is ideal for open terrain sight recognition You can select only the inner lights flashing for a more subdued signal All the lights flash in an on/off sequence for a bright visual appearance. You can switch on only the outer lights flashing for subdued marking Also, all 5 lights can flash in a high-speed sequence to create maximum visibility while in deep undergrowth or in a heavily wooded area. The Flasher Marker System offers you the choice of options specific to your personal needs. Powered by 2AA Alkaline batteries (not included) this light will operate for over 200 continuous hours and can be seen from up to 2500 feet. This is the right size and right weight light for affixing onto your pack, on your belt, or for using on your mountain bike with the "included" mounting bracket. The Flasher Marker System includes two lens caps, red and amber, and is fitted with a molded super strong open-end belt clip. Also included is a black elastic armband so you can choose to wear high up on your arm for better visibility.