ER08, smartring with ECG, Review

The ER08 is a many ways nice smart-ring, unfortunately offering very coarse monitoring only., limiting the target group of users drastically.

Its claim to fame is ECG as indicated by the small drawing on the ring.

The first I noticed was the very smooth and pleasant feeling of the material, slides much easier on/of the finger than e.g the R13 of the same size.

It is also some epoxy resin over the circuitry, but does not ‘stick’ to the skin at all.

The ER08 is 8.2mm wide, and 2.7mm thick almost all over. At the tiny ø2mm electrodes for the ECG it is 3.4mm, but they should be kept on the soft underside of the finger so they are not felt at all. I The size #11 got has an inner diameter of 20.6mm and weighs in at 4.12g. Note in the specs below that they have two battery-sizes 0.135Wh and 0.200Wh over their quite wide range of rings from #6 to #14, I don’t know at what size the split is. Most surprising is perhaps that they use different voltage.

ECG

The ER08 can do ECG as they claim, though the signal to noise ratio is obviously much poorer than e.g. a Polar H9/H10 breast-band, simply due to being so far from the heart.
And be aware that it (like smartwatches) requires the use of both hands, so individual measurements, no monitoring. (click to enlarge image)

It is important that the two hands do not touch during measuring, but the (index) finger on the other hand only touches the marked contact-area, and not the skin.

Note that if you try shortly after charging to 100% it strangely seems to drown in noise, I’m not sure what that is all about? A GUESS is that it needs some minutes to get to body temperature, or that the battery need to ‘stabilise’ a bit after the (quite fast) charging. I’ve seen it more than once. But If I try after a few hours it works just fine.

It is obviously crucial that it is used correctly for them to be able to have a suitable signal to noise ratio to do an analysis. If the ring sits tight on your finger there will be no need to do anything special. If slightly loose and you just press hard on the top of the ring worn on a free finger, to ensure a good contact, you might push the ring to a point where the contact on the underside of the finger might slip fully or partly…
I currently wear it on the middle finger, and by pressing the ring upwards towards the finger a bit using the neighbouring fingers, I can get good contact with a light press by the index finger of my right hand on the top electrode

Looks a bit silly but is easy to do, and works. I guess each person will quickly find a way that gives the best signal to noise ratio possible.

I have no idea of the quality of the analysis they do on the ECG data (Requires the app to be allowed network access…).

App and other health

It uses the HealthWear app, nothing fancy in it, but seems much more stable than many of the other apps used by other cheap rings/watches. 😎
Compared to the horrible and horrible slow “ECTRI” used by the R13, the HealthWear is a dream!!

Apart from it’s main attraction the ECG, it also offers the usual Steps, Heart-Rate, SpO2, Sleep and Temperature. The biggest problem is the coarse monitoring.
You can select every 60/50/40 or 30 minute, but not less coarse than that!! So though it might work to ‘monitor’ a rather sedentary person, it really limits the usability.

It does a quite good job at detecting the sleep period, and even catching when I doze of in a chair and awake periods, but like for so many other devices, I would suggest to just ignore the rest of the claimed sleep-details. I’m currently composing a test of a few devices, will be here.

It claims to also do BloodPressure and BloodGlucose. The BG is at the least 99% fiction!! and I doubt the BP got a much better connection to reality!!
The BG show three neat daily peeks, no matter that I almost never have three daily meals (and didn’t in that period), and claims three peaks even at days where I ate and drank absolutely nothing to test it!!! Opposite that at Oct. 1. I had a friend for dinner and we ate and drank heavily from 19 to 01, and this is not reflected at all either….
So this is just AI-garbage hallucinations!!

Here a collage, and the screendumps behind it, the hole in 2025-09-27 was charging. (click to enlarge)

Battery

Due to the quite coarse monitoring it lasts REALLY long on charge for a cheap smart ring. Set at the least coarse (30 min) it lasted my 7 days (+ an hour). Note though that the percentages is rather misleading as it oddly turns itself off, somewhere around the 20% mark.

Slightly over five days after charge it said “48%” in the app.

One surprising thing is that it charges fast! 20 to 61% did not take more than some 10-15 minutes, and 61 to 84 took 10 minutes and less than 10% from that to 100%

Specs

Here some specs from their listing.

Conclusion

It is a quite nice ring if you are not too active. For active persons it will not really do the trick, due to the coarse monitoring.
On the other hand it is an easy way to do an ECG, though the signal to noise ratio in that is not great, so I doubt much details can be pulled from it Though skipped beats or very irregular beating should be possible to spot.