This small taillight is really very convenient because small and you can always have it. It does not need additional support and also looks good. The luminosity I guess a little less than a larger and fixed mounted rear lights but as a last resort when one is "surprised" by the dark and / or 2.Rücklicht, as I almost always use it to very good use. Whether the Mini batteries last type 2032 long, I can not say, at least you get them everywhere low. The processing seems to be pretty good.
