idem FCC Certified, Rechargeable Smart Bike Taillight That Turns On and Off Automatically, Deceleration Signal When Bike Slows Down Abruptly, SOS Distress Light, and Optional Theft-Deterrent Alarm.

This is one hell of a great light. It is extremely bright and all the features work great--like the braking feature, SOS 'fallen and I can't get up' feature, However there are two features which I don't like.1. The alarm works perfectly, but it will raise the dead! When you turn the light on/off, the alarm beeps once--enough to startle everyone on the train when commuting. That one beep wakes everyone up.On several occasions the alarm went off accidently and I couldn't stop it. It happened once at a Home Depot in Manhattan and all the security guards had to come over. I literally had to take my jacket off to muffle it while I ran out of the store. On another occasion it went off at a bike shop and deafened the poor mechanic and everyone in the shop. They told me that they had to take it out in the back yard until the battery ran out.So far I have purchased about ten of these lights because they are so good and so efficient but I open them up and cut the wire to the buzzer.If you purchase this light make sure and use the tethered rubber cap to keep water out of the micro-USB charging port or else water will quickly damage the port.

Solid, sturdy. Installs on seatpost easily. The alarm and beep when turning on is very loud. The flaw is that you need to remove a small screw with an Allen wrench in order to remove the unit for charging. It is impractical to charge it on the bike-the supplied cord is only 6" long., and the port is not easily accessible. I have taken to balancing an external charging battery on the seat, in order to charge the unit. Until the design makes it easily removable for charging, I cannot recommend this product. It is a shame because it works well in other ways. Perhaps a helmet mount would make it easier to charge????

Good product and design for what it is intended to do.Not visible in daylight. For that you need something like the Cygolite Hotshot– 100.Since it is designed to be an alarm system, it has to stay on the bike, and thus is permanently attached to it: it may attract a thief, and also it makes it hard to recharge, since you have to do it while installed on the bike.

Brilliant product. Everything works practically as described. Seriously. Everything. Impressive.Imo, best location to install this unit is under the saddle with the bracket supplied. But the bracket works only with regular round saddle rails. I have a carbon saddle rail which is oval. Will not fit. So I have to stick to seat post mounting option. But that's no reason to take off a star.

I got this mostly for the automatic brake feature. Unfortunately, it doesn't work as well as I expected. It only activates when I brake abruptly or accelerate rapidly. It doesn't light up at all when I'm coming to a stop from any speed unless I slam the brakes hard. I thought maybe the angle of the light was an issue, but even when the light was parallel to the ground, it wouldn't activate when slowing down.Also, when mounted under the seat, the charge port is blocked by the seat rail. This means you have to remove a security screw before unclipping it for charging. I suppose it wouldn't be a problem if you didn't use the little tapered security screw that holds the light to the mount, but then anyone could just easily unclip the light and smash it to disable the alarm.I wouldn't recommend this product if you intend to mount it as pictured (under the seat) or want a reliable braking feature. I'm pretty sure the first time I charge this thing, it'll probably not be worth the effort putting it back on the bike.Advice for the manufacturer:Relocate the charge port where it's accessible in any mounting positionBe able to adjust the sensitivity of the automatic braking featureChange the terms for "night mode" and "all day mode" (it doesn't make sense that the light doesn't flash all the time in night mode and does in day mode)

This rear bike works Great and I don't even know that it has an alarm.I just have a little trouble setting the alarmThanks

Very nice product, very bright and I like the way it turns on and off automatically so you don't have to remember to turn it on or off and is rechargeable.

This is the best product for the money! Quality is perfect, the tail light can be fixed on a seat post or on a saddle - both brackets are supplied. Very bright and deceleration sensor works ideally and turns on the brake light mode just in time! I purchased 4 or 5 various tail lights including with deceleration sensor and none of them worked properly. Had to returned all of them. But this light does its job just perfectly. Price is very reasonable!