I compete in marathons so I have to run and cycle evening after work to stay in shape. Too often I've had a maniac driver just about hit me so I needed to find some kind of light that wasn't heavy but that drivers would see. I found this one on a google search and didn't expect much for the price but was very pleasantly surprised. Now I don't train at night without it. I wish the marathon bags would donate one to all of the runners to help keep them safe while training.