I walk every morning at 4 am, and my route is dark, at least fo the first half. I'm not sure why, but there are no street lights on my street. I walk on the side walk, but I still have some concerns of visibility. This is the absolute perfect solution. It fits snug on any area, my ankle, wrist, upper arm. It is like one of those snap wrist bands, it adapts perfect to any area and you don't have to latch it. The light is run via a cell battery, and they include an extra one. How is that for convenience? The on/off button is located right on the cuff and easy to manipulate. One push turns it on, second push starts it flashing, third push turns it off. The light is bright, easy to see. It is not tight at all, just comfortably snug. Very well protected, making it impervious to weather conditions. Excellent addition to your workout routine.