With the dark days of a Glasgow winter approaching, I wanted additional light to keep me visible on my commute. This has worked well. It has four modes, in which you can have flashing or steady lights in any combination (e.g. red flash, white steady; white steady, red steady). Don't expect the white light to help you see the road, but if you mount it in a good spot, it is handy and bright enough for spotlighting your bike lock or shed while stationary. Also, it is very easy to mount on the helmet. But don't forget to look at the instructions--there's a plastic bit keeping the batteries apart that you'll want to remove before mounting the light. Also, so far, it hasn't been destroyed by the rain (about seven rides so far in wet weather).