Daniel O.wrote a review of Portland Design Works Danger Zone Tail Light on January 24, 2013
Best rear light I have found. In use for two years on (especially) night and even day riding on New England roads. (bike lanes are rare to non-existent)
I have actually had many people clear a full lane when passing later advising that they thought it was the rear light from a police stop.
You will not be disappointed. Six stars please!