One of the few lights that will mount on a back rack... or at least mount on my back rack. There's a self-tapping (meaning, when you screw the screw in, it's cutting threads to grip to in the light) screw and a matching hole, plus a prong to go in the bottom hole of the rack so it doesn't rotate. It makes the lightswitch a little hard to get to, however.
It's also one of the few lights that has a CSPC reflector. Now, I think that the CSPC reflector standard is pretty lame, but it's better than nothing at all. The law requires that I have both a reflector and a light in the back and I think that it's fairly reasonable. It's in the same vein as the ViewPoint FlashPoint High Intensity Taillight, except the ViewPoint light is brighter. I've read on the Internet that the PlanetBike Rack Blinky 5 is brighter but haven't tried to compare the two.
It takes two AAA batteries and has a nice long battery life.
Right now, it lives on my rack, except that the button broke.