I am an avid runner and my runs take place at 4:30am. No matter what the season, it is pitch black. For my safety as well as a courtesy to drivers, I wear two of these lights. These lights are extremely bright! It's like my body is surrounded by a halo. They are easy to use and will last for a long time. If you need to change the battery (that hasn't happened yet of course), it's super simple. If you run or walk in the dark, you MUST get them!