I bought these for both running and cycling. I do both early and late during the day when the sun isn't always shining and it's nice to have a bit more reflection, even if it is extremely dorky.
These arm/legbands are simple and don't really need explanation. You press the button and the LEDs flash, you press it again, they stay on solid and press the button again, they're off. The 3M reflective material is high quality and does a good job at catching headlamps and alerting cars.
The only problem is that the wiring for these is in a little elastic pouch which, if it's raining, will get wet and your batteries will short out. Mine dried out and started working again, but it's something to be aware of.
Overall, if you need something like this, buy these because they're no more expensive than they need to be and they do just exactly what they're supposed to.