See.Sense Ace ANT+ rear light.

[cougie uk]

They're my go-to lights. Light and bright. I used the app to set up the lights as I wanted with their patterns and then rarely open the app again. Battery life seems good and customer service is good too. One light failed on me and I got a replacement straight away.

Outlasted my lezyne light on the Brompton too.

 

[Juliansou]

Got sent a free pair as an incentive to join BC. Was considering joining anyway so this was a nice bonus. Lights, as a piece of hardware, can’t be faulted. They are drastically let down by the software & app (iPhone) & customer service. Nice as a freebie but if I’d handed over cash, I’d be sending them back for a refund. Just use them as a nice set of lights & they do the job.

 

[Glasgow]

The See.Sense Ace rear light is currently £17.99 at ProBikeKit.
https://www.probikekit.co.uk/cycling-accessories-nc/see.sense-ace-rear-light/11793127.html
10% off with code BIKE10 makes it £16.19

I've just ordered one as a spare despite mixed experiences with See.Sense lights...

I bought an Icon2 which fell off repeatedly and got lost eventually, See.Sense gaslighted me by denying their lights fall off and sending me some videos of their lights not falling off (who needs to make videos of a light not falling off?). Several reviews on their website confirm that they fall off.
I replaced it with an Ace (which I won in a competition, I wasn't giving them more of my money after that experience!) which has been excellent; it's plenty bright enough, has a longer battery life than the Icon2 (despite See.Sense's claims for the Icon2) and has never fallen off. The Android app seems reliable these days though other than changing the flash pattern and light intensity it doesn't do anything).
I don't understand the claimed smart features - the brake light function works well (unless you set the light to constant), the crash alert doesn't work at all, I've never used the alarm (it seems pointless because it only works if you're close enough for Bluetooth to connect).
Also, although mine has never fallen off the elastic bands it attaches with are crap - mine snapped when I first fitted it, so I selected a bigger size which lets it waggle about.

What I'm saying is: it's a decent, cheap light for £16. I wouldn't pay anything close to full price though.