I have this red light in the rear, and their white light in the front. I like these lights, they're very bright, visible from wide angles, and they look great on my bike even when they're not on. I take visibility seriously as a biker, and I do not feel safe riding on the same roads with vehicles without bright lights, and I feel safe riding with these.It's not perfect, however. The overall construction of the lights feels pretty shoddy honestly. I would have paid quite a premium to get these exact lights with a hearty aluminum housing, glass lens, and rubber gaskets, but instead I paid like $13 and got this. Plastic-covered plastic with some plastic on top. I've had them for over a year, whacked them, doused them, and dropped them a few times, and they have not broken on me. Perhaps my mistrust of their construction is unfounded, but they feel cheap in the hand, and I suspect they are only BARELY water-resistant. I expect these to break any day now, but I also have another identical backup set and I'd re-purchase these the same day if they broke, so I guess I don't mind all that much.There are a few different light modes like the store page says, Solid Low/Mid/High, Dim Flashing/Bright Flashing, and Strobe. The manual included with the lights includes a little more information such as the approximate runtime for each mode, which brings me to my main complaint about these lights, which is less of a complaint than an observation: The battery life is a joke.It's not really their fault, it's a design constraint. Small lights have even smaller batteries, it's the price you pay for the slim form factor and sleek aesthetic, but it's a bummer nonetheless. When you look at the run times for the different light modes, it becomes obvious that the Dim Flash mode is the only one worth using. The steady beam and strobe modes get less than half the battery life, so don't even bother with them. Use Dim Flashing or Bright Flashing, and you can expect to run these for 4 - 5 hours on a single charge, which is honestly great for most of us most of the time.But I have had them die on me in very unfortunate times. Once on a particularly long ride they died halfway home at around 7pm on a rainy day. I was losing daylight fast and the last thing I wanted was to be on the shoulder of a busy road, in the dark, in the rain, WITH NO TAIL LIGHT. It was a harrowing experience, but again, not the light's fault really. I rode for 6 hours that day, I should have known they weren't going to last the whole time.But I have a plan. Like I mentioned, I have a spare set of these. I've disassembled one of them and plan to modify it somewhat. I'm removing the puny ~500mAh 3.7v lithium battery and running some wiring out of the USB charging port (sealing with hot glue or something) to an external battery with about 10x the capacity. I'm doing this for the front and rear lights and running the wiring as neatly as I can to a central battery, so I should be able to run these all day long on Strobe Mode without worrying about making it back before they die. I'll report back if this project is successful.EDIT: Two years later and I can comfortably recommend these, I have bought several sets now. The original set still works and I use them all the time. The battery life started to decline to around ~3 hours and that became unacceptable to me so I finally did that battery mod I mentioned. The internal battery on these is 500mAh and I removed it, soldered my own wiring in, and bought a 3,700mAh battery at the same voltage and wired both the front and rear lights into it. I haven't fully stress tested this yet, but it works great and my math says this should get me something like 15-18 hours of both lights running constantly on slow blink mode. No complaints.