First, this light is huge, and can seen from the back and sides. I love the attachment mechanism - it stays in place and is easy to mount and un-mount. I have owned a number of Knog lights over the years and this is on par with those. Put another way, if you like other Knog lights you'll probably like this one as well. It's a little pricey, but can you really put a price on being seen? Worth every penny in my opinion.
I give this light a split star rating. Five stars for the light itself. The light is very bright and well seen from the side and rear. I gave it a four star rating due to the attachment system which is a rubber band. I would prefer a clamp, but it has not been a problem on the gravel roads I travel. Easily charged with the supplied cord or a direct plug into a USB port.
Im on my second one of these since October and now its about to go back. Fits my aero seat post, is Fantastically cool looking and bright but as soon as you hit a little rain, game over. Works again after it dries out but battery life is tremendously shortened. So disappointed.