I just picked up a Serfas UTL-6 Thunderbolt to mount on my saddlebag. It's got multiple led's and no focusing lens so it's non-directional and painfully bright. From a distance it's no brighter than my Superflash straight back, but at 80 degrees to either side it's still as bright. The battery doesn't last much longer than my headlight, and that worries me some, but my plan is to charge it at the same time as the headlight. It mounts with two silicone straps which reassures me about keeping it.