Review on OMKHE Running Light for Runners (2 Pack) Rechargeable Armband Reflective Running Gear, LED Light Up Band for Joggers, Bikers, and Walkers by Derrick Feliciano

They're a bit cheap but do the job. I carry them on my arms when I run and feel like they make me much more visible than no light at all. I charge them every day so they don't die. As others have pointed out, plugging them in for charging is oddly difficult. It's also worth noting that the light actually only covers about 2/3 of the strap, the rest is Velcro/strap material. That's why I have to consciously make sure when wearing it that the light is really visible from the front and behind.