G Keni Smart Rear Bike Lights for Night Riding, Ultra Bright Brake Sensing Bicycle Light Back, Auto On/Off Bike Tail Lights, IPX6 Waterproof, USB Rechargeable, LED Warning Cycling Safety Bike Lights

These lights are fantastic! I’ve been really impressed with how long the battery lasts—it’s been weeks and they’re still going strong with regular use. That alone makes them worth it.What I love most is the automatic on/off feature. They’re smart enough to sense the ambient light, so they only turn on when it’s dark, which saves battery and adds convenience. I’ve placed a few around the house—in the hallway, pantry, and bathroom—and they light up just at the right time, without me having to do anything.They give off a nice, soft glow that’s perfect for nighttime visibility without being too harsh. Super easy to install and move around, too.If you’re looking for motion-sensing lights that are efficient, reliable, and low maintenance, these are a great choice. I’ll definitely be ordering more!

I have several of these tail lights. First of all - I'm pretty sure it is powered by alien technology because although it says 50 hours of run time in the description - I've 100% used it way longer than that without charging it. It is currently March and the last time I charged this light was in the fall some time - I've used it a bunch of times since then - and TWO DAYS ago I accidentally left it on in mode 3... just checked and it is STILL FLASHING!!! That is like 48 hours later.... how? HOW?!!Someone said, 'Can I give it 6 stars?'... and I can not agree more. This is literally the best purchase you will make for your bike ever. Buy one for all of your bikes. And no, this is not a paid review. I just really love this thing. (FYI, I always use mode 3 - the flashing mode that gets brighter when you stop. I can't say how the other modes do on the battery life.)

Easily mounts under the seat. It feels secure, and like a less likely target for theft. The light itself screws off nicely when you need to charge it, or just take it with you.I like that it's rechargeable via USB-C. It holds a charge for a VERY long time.My only complaint is that I wish it was a touch brighter. It is visible enough for many uses, but maybe lacking for some specific circumstances.

Initial impressions: light has good brightness at night almost blinding up close, but only just adequate for daytime visibility. Annoying restrictions limit how you use the modes. For example, slow blink and breathing mode must use auto on/off and the light gets disabled during the daytime. Fast blink and solid mode cannot use auto on/off but do not turn off during the daytime.This seems like a major oversight and defeats the whole point of an auto on/off feature, I have no idea why you would want to disable the rear light during the daytime even if it does save battery life. Also if it's a cloudy day or there's low light you would want the light to be on but the light may or may not disable itself depending on how much ambient light it senses. So your light could actually be off when you think it's on because of 1) the auto off feature and 2) the mode you're using is disabled during the daytime. For these reasons I only use fast blink or solid mode which do not use auto on/off and stay on day or night.All modes still allow the light to brighten while braking and it's sensitive and actually works very well. Just touching the brakes slightly will brighten the light quickly, it almost feels like the brake lights on a car. However, it is frustrating that the light can only get very bright like this momentarily when braking.The auto on/off is too fast and shuts off after about 20 seconds of no movement. This could be bad at night if your light is constantly turning off when waiting at a standstill for longer than 20 seconds. Also you have to trust that the auto on feature is working properly otherwise the light might be off when you are riding.note: the instructions are unclear and don't explain that you can change the three brightness levels by holding the button while in solid light mode. The only setting I found useful was the highest and the other two settings are too dim.These are just the issues I noticed but otherwise it is built quite well and appears solidly attached to the metal seatrail mount. If you don't mind being limited to just the fast blink and solid modes so that the light can be on at all times then it is a great rear light.One tip for mounting to the seatrail, you can mount the seatrail hanger on top or below the seatrail. This will adjust how high or low the light sits beneath your seat by about an inch or so. Mounting the light higher tucks it in better but it is slightly less visible than mounting it lower.

So, I love this light for some very specific reasons: 1) the build quality seems very good - aluminum body and bracket; 2) big enough to give out enough lumens and multi-mode lighting; 3) rechargeable battery; 4) most importantly - which is why I bought it - I wanted something that I could semi-permanently screw/mount to my bike rack so I didn't have to worry about losing it, having to take it on/off and it would be there whenever I needed it. I was about to purchase the Blue Lug KOMA from another online retailer (I had waited 3 months for it to come back in stock) but it is smaller, less bright, less lighting modes and a lot more money - $50 with shipping!After looking around I found this light and thought - hoped - that I could retro fit it to bolt to my rack and it worked great. I had to remove the mounting braket with two tiny screws....BUT that wasn't easy - they are small, easy to strip, and they were probably lock-tited on there....but I got them out and the bracket off. If I hadn't been able to get them out, I would have just had to use it like any other strap-mounted light - which would have been fine, but not why I chose this particular light.Then all I had to do was to drill a small hole through the aluminum mounting base, and attach it to the rack - which is why I bought this light - the METAL base - so I could drill through it and not deal with any plastic crap mounted light. Did it void any warranty? Probably yup. Do I care? Nope - it is mounted exactly where I want and how I needed it, at a fraction of the cost of the KOMA. I will probably buy one or two more to put on my other bikes. I can't speak to the long-term durability, battery life or anything else (other people have already reviewed that), but for the price and my specific needs, this is a 6-star buy. See the photos for details....