EGear Tag-It Dual Function Signal Light
The same great quality as the Guardian light now with a convenient carabiner clip casing.  Visible up to two miles away, very lightweight yet tough and durable!  It will not restrict movement and may be attached anywhere.  Affordable, wearable safety whenever you need to be seen in the dark and since it's waterproof, it will not be affected by rain or complete submersion.  Great for bikers, hikers, kayakers, horesback riders, children, pets...any application where visibility in the dark is a safety concern.  Just clip on and go!  To switch from flashing mode to steady on simply flip the batteries.