It's a Cateye...,
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This review is from: Cateye Rear Battery-Powered Bike Light TL-LD 130, Red (Sports)
Tough, waterproof and bright. Cateye have a reputation for quality because of lights like this.
This model has three modes - flashing, a pattern that makes me think of an old school Battlestar Galactica Cylon with technical problems, or plain old on. The light comes with a good quality slide clip to fix it to a backpack or saddle bag, but putting it on a frame/seat post requires either the purchase of a separate clip or (much cheaper) a couple of old hairbands.
At this price you have no excuse for not being seen. Not to mention that it's actually illegal to cycle without lights at night.