Python client for the $20 Colmi R02 smart ring

From the little bit of research I just did before buying one, most people are reporting that compared to their more expensive trackers, the heart rate, accelerometer, and sleep tracking functionality are all pretty accurate (good sleep tracking being dependent on a high sampling rate, which decreases battery life), but the blood oxygen and "stress" reporting is uselessly inaccurate.

That has also been my experience with this model. I’ve been using it for about a month now. I originally planned on trying to use the accelerometer data over Bluetooth to build a custom control input for Frame smart glasses, but I got busy and never got around to that. But I’ve been wearing it as a health tracker and the heart rate and sleep tracking seem pretty accurate relative to my Apple Watch, and the blood oxygen measurement is generally a couple percentage lower than my Apple Watch. I have no idea what the stress thing is even supposed to measure, it’s just a random number that doesn’t seem to have any correlation with real life and there’s no units or explanation.

I get about four days of battery life with all of the sensors turned up to maximum frequency, which is every 5 minutes at least for the heart rate. Surprisingly good for such a small lightweight device. I imagine it could go a lot longer if you turned down the sensors to a lower frequency. I found a good rhythm is to charge it when I take showers, that seems to be a good balance and it never comes close to dying. My Apple Watch on the other hand regularly dies before I go to bed, and I can’t wear it for sleep tracking because it can’t last that long.

I will never understand people that pay a monthly subscription to access basic local sensor information like this. Yet I see people wearing subscription-based smart rings all the time. I don’t get it.

Some reviews say it's a little bulky to wear. It's that your experience?

I tried blood oxygen and the readings were the same as my pulse oximeter (though it always shows 98%, so I haven't managed to test any other value), but my sleep reporting with the ring would regularly be three or four hours longer than I actually slept, making it useless.

> test any other value

Try this:

Hyperventilate for a minute or two. Then, make a full exhale and hold it. You should be able to hold your breath for longer than you normally can and during this time you should see the value drop a bit. Be sure to inhale before you start getting dizzy or faint. (Note: do not do this under water)

Oh interesting, thank you, I'll try that.

> (Note: do not do this under water)

Or while operating heavy machinery.

It's a bit thicker than my normal wedding ring, but its also a lot lighter weight. I don't really notice the difference enough to mind. I suppose if you're not already used to wearing a ring it might take more effort to get used to.

They come in different sizes and they don't necessarily correspond to standard USA ring sizes, so it takes some effort to measure and make sure you get the right one. But the effort is worth it to get a comfortable fit. And they are cheap enough that you can always buy multiple different sizes. I think I paid like $11 for mine on Taobao with free shipping (part of that may have been a discount since I was a new customer).

It only samples heart rate every 5min? While I can't get disappointed over a $20 device, that really limits the utility of the heart rate data.

It samples heart rate every 5-30 minutes in the background (for long term tracking and sleep), or continuously while you're asking it to do so, same as any common smart watch. There's a command to begin realtime heart rate reporting, and a command to stop it.