Cycling Plus reviewed these a couple of months ago, not cheap (£50ish) but they seem fairly good & battery free, and a straightforward rear light alternative to a rear dynamo light.
Already got a front dynamo on my do everything road bike, and would like to find something similar for the rear, but the hub dynamo is a Shimano model that doesn't have the output for a rear light (2.4v rather than 3v).
Independent user opinion of a Reelight would be appreciated.
