I've noticed this site is advertising this particular light quite a bit, and figured I'd make a few comments for those looking for lighting options.
I purchased this light about a year ago after a decent amount of research. I have been quite pleased with its specs for night time brevets. I have 2 of them strapped to my fork and use one at a time. When one runs out, I have the backup ready to go. I did a full SR series and 1200k last year with these lights. On the 1200k that started in the late afternoon and required plenty of nighttime riding, I only used 4 AA lithium batteries.
- The light on high lasts 6 hours on 2 AA Energizer Lithium batteries.
- Lightweight, waterproof, and durable.
- Has a low and medium setting. I use the low setting when climbing and the runtime is stated at 71 hours, probably much longer on lithiums. I use the medium setting when riding with others, as high is typically too bright and distracting to others when riding in a group. Medium setting spec is 13 hours. I never use the turbo setting.
- They double as flashlights at home when not riding.
- Reasonably priced. ~$60/each.
It's been a year, so there is probably a better light out there due to the rapid advance of LED technology; however, this one has some real life testing behind it.