Top positive review
Excellent light, rechargeable via USB
on 12 May 2015
This is an incredibly small and light red light for your bike. Noting that the image show is (wrongly) a white light, This mounts easily on my cycle helmet aiming backwards, with the fixing being strong by stretchy rubber material that is fiddly when stretching around the vents on an helmet, but only takes a minute or so. I would expect you could fit this to any helmet or bike. The size of the light is about the same as a small matchbox, so really tiny.
The light is incredibly bright and has different light patterns, including flashing lights. I'd say it is easily visible from a few hundred metres away by any passing car.
Usefully, the light charges via USB in only a couple of hours. Once charged, the light (on flash) operates for at least 6 hours (my longest ride), and I would be surprised if it didn't last 8 hours or more between charges. Charging is done via a mini-USB rather than that micro-USB we tend to see on recent smartphones.
Fitment to a bike is very easy, and once fixed it wont move or fall off. Note, however, if you fix this to your seat post it the LEDs will be vertical, i.e rotated by 90 degrees from the image displayed. I've ridden with the bike in the rain, and it's not affected the working of the light or later charging. The USB connector for charging is covered by the rubber cover, and this fits well to protect against water ingress.
In summary, an excellent light that is very small, easy to fit and swap between bikes, and is rechargeable via USB. Well recommended, as a main rear light or as a emergency backup.