Bright, easy to attach but doesn't hold charge when cold. A full charge will last 3 half hour commutes, unless it get cold overnight. I leave the bike in an unheated shed and even with a full charge it will be dead the next morning if it get cold, low 40's.
It's a great, basic, rechargeable taillight that lasts a good long time on flashing mode. People see it readily and it attaches to the seat post easily via its rubberized strap. Easy to remove and charge via a USB cable. A nice combination of usefulness, ease of use, and intelligent design. Only caveats are I wonder how many years the rubberized strap will last.
I gave this a two only because when it does work it's bright and attaches to my bike ok.
If I don't charge it before I ride it doesn't work. Sometimes it just doesn't plain work at all. Very disappointed and would not recommend this. I would rate this light as extremely unreliable.
Just such a smart design. The onoff switch is the lens, just tap it twice. And to select another light mode is also the lens, just tap it once. USB rechargeable, but the smartest thing about this light that it is angled, so once you tighten the rubber band around your set post it will shine backwards, and not down to the ground light most other taillights will do. Also lightweight and you won't run out of battery soon with the 35 hour runtime.
Wildly simple to attach, move and use. Charged it once two weeks ago, haven't had to charge it yet. Simple operation (I often forget to start it before the ride, easy to simply reach down and double-tap the lens to get it going). Only improvement I could ask for is a slower flash mode - the flash mode lasts forever, but it's a little frenetic for anyone following. Slower-paced flash would be great. Still a great product.
Can't ask for more in a taillight. I can use it for two hours a day for at least 2 weeks without having to charge. This is perfect. Super easy to swap between bikes too. I put it on my wishbone seat stay or bridging two normal seat stays.
Good rechargeable light. The strobe mode is obnoxious to fellow road users but the pulse mode works well. Lasts a good long time in pulse mode compared to other rechargeables.
One issue is that the USB rubber cover is not captive and mine was lost months ago. USB port now filling with road grit.
I commute year-around and in the winter it is completely dark on the way home. I like to have two independent tail lights in case one goes out along the way. It is lightweight, easily attaches securely to the seat post and has been trouble free half way through the winter. I'm not sure one of these is bright enough for night riding on roads with speed limits exceeding 30 MPH hence the four star rating instead of five.
Not the brightest on the market, but perfectly adequate. Lightweight and fits on seatpost. I am 5'4 so have limited real estate on seatpost, but this light is visible, not obstructed by seatbag either.