"Laser" safety lights each with super bright LEDs run by (2) "AA" batteries that you supply. It's square and has a flashing or steady LED lamp visible up to 2500 feet (distance may be exaggerated). A 2" x 2-1/2" red plastic reflecting lens covers (3) lamps. Hook it on your belt or pack with the belt clip, use the included elastic strap for arm or leg mounting, or the included aluminum flange to attach it to your bike. It's great for general use as a warning device or as an emergency signal for roadside breakdowns.