Merely 7.8mm thick (6.9 excluding small protrusion, and down to 4.0mm at the edge), AMOLED with AOD.
By far the most wearable smart watch I’ve ever seen!!
Update: Currently at $30 including shipping….
(This post is an ongoing project, the last added was pictures of a disassembled unit)
This is grown a bit over the months, so first a
Less than 7mm thick
Over 3 weeks stamina, with all monitoring ON
All metal. (Zinc alloy I believe – Nickel free)
About $30, including shipping (less any local taxes)
The 1.3″ AMOLED display, can be used with AOD, though that hits the stamina.
No NFC or GPS
Software works, but it’s weak.
- All the usual HeartRate+Sleep+SpO2 monitoring, but BloodPressure also.
- Works offline without a phone. Holds data 6+ days for fetching into the app later. (No known limits inside the app)
- The usual sports stuff, plus some period stuff – both out of my scope.
- The usual notification stuff, call control and camera control, if hooked to a phone.
- No mic, speaker jack nor SIM-slot.
- Three colour variants: ‘Gold’, ‘Silver’ and ‘Black’ (+bands, 20mm std.)
- Arm difference 2023/2022. arm-to-arm length 48/50 mm.
- Hardened glass, possibly Gorilla Glass, or a competitor
The longer version…
I got really exited when I found this one. ø43mm, and only 7.8mm thick, and 6.9mm outside the 20mm protrusion, 1.3″ 360×360 pixels AMOLED display (277PPI).
(The mean thickness as volume divided by area is 6.5mm, see later on that)
At first I thought that this was almost too good to be true, But it is real, and at the price it is surprisingly good value for money for US$38 (including shipping and 25% VAT) – that is about $30 with shipping, but ex VAT. And after four months my excitement is still high. Sure it is not perfect. But in my book there are NONE of the other I would rather have, no matter the price!! And NO it does NOT have a cheap plastic feeling to it, all metal case and band, with no complaints on workmanship. But the software/firmware are where it is weakest.
Sold as “2022 New Ultra Thin Smart Watch Women“, the “T8” is on the box. I bought it here. (The price vary wildly from different vendors, and over time, so browse a bit before buying….)
ADD 20230304 Adjusted prices above, prices have fallen 20% e.g. here since I originally bought the first three months ago. And the listing says “2023”, so not sure if it is a new variant, or just an advertising trick – ordered one to check it out… – ADD: It was close to same model, the 2023 has shorter ‘arms’.
ADD 20230324 Adjusted prices above, prices have fallen 32% e.g. here since I originally bought the first three December/January. This listing was a scammer
ADD 20230410 Adjusted prices above, prices have fallen a little further since 20230304. The lowest I found today was here, at $31,
I’m far from sure,
but I THINK the brand is “Azhuo”. See e.g. here, and here. But they offer people to put their own brands on them if they buy 100+, so I guess that is why all advertising images, the retail box and manual are all ‘Anonymous’. But as Azhuo is also a wholesaler, it might be that it is another manufacturer that is actually behind the T8.
ADD it could well be that the actual producer is Sovogue see e.g. this, as they offer 6 colour-variations (versus 4 at Azhuo). Especially a black case&band.
One could fear that such a thin unit would have a very short stamina. Not so!! With my usage pattern, it is 3-4 weeks !
Physical design and wearability.
Beyond the ø43mm, the band ‘arms’ stick out a bit, so the length ends at 50mm for the 2022 version, 48mm on the 2023, making it less suitable for lesser arms, though they do also point downwards.
And they also try to make the display coverage appear larger
(Notice how the top right “0” of “200” reaches just outside the display area and have been clipped, and the slightly grey display area, showing the actually active display size)
The actual display coverage is 59% of edge to edge, and 68% of the glass surface (5mm bezel, including a 3.5mm bezel-ring under the glass)
Here I’ve added a thin green ring to make it more clear
The case is unfortunately only available in a glossy golden, ‘silver’ and black – But the golden is a rose-gold not too far from the skin colour of a pale European. I would have preferred a mate case finish over the glossy one. But at the least the band (and clasp) is not glossy. I have considered using a glass-brush, to scratch the case surface mate, time will show if I will…
The quality of the ‘gold’ plating (or whatever it is) time will tell. (no visible wear after five months)
Luckily It uses a standard 20mm band, so easy to swap to something else when/if it gets ugly.
The band has a neatly looking closing mechanism:
The mechanism is a bit complex to mount around the arm with one hand – but I guess that is just a matter of getting used to it. If your hand can curl enough, a hint is to lock the band in the outermost position when taking it off, so it is only a matter of tightening with one hand when back on.
The T8 is sold in three colour variants (plus the same cases with different bands)
(Still with various protective plastic on)
I’m not sure what material the band and case are made of. I have seen “Alloy” and “Zinc alloy” in various listings. It does not react on magnets. (Well part of the buckle, and the small band attachment-ends do react slightly to magnets). This goes for all above colour variants and their bands.
Usually my skin reacts in a few days if a watch/band contains Nickel, I have NOT had this on the ‘gold’ variant, so if present it is in low concentration… 🙂
(ADD: After over four months daily usage, still no skin irritation, so none or minute amounts of Nickel)
The case thickness also makes it very wearable, as the centre part ‘sinks’ into the arm, even when not wearing the watch tight:
Note how close the mesh band goes to the connection pins on the front side. Most Milanese mesh bands end in some clumsy chunk. (I’m yet to find a Milanese LOOP band that has such a nice ending…)
As can be seen on the last of these images of the 2022 model there is quite a distance between the case and the band. And though this seems silly at first it DO allow for the usage of a Milanese LOOP band, directly around the pin, without the usually ugly ‘connection piece’.
ADD 20230519 Surprisingly the newer ones from 2023 has 1.5mm shorter arms, so ends at 48mm total length, and looks better. You can still use loop bands directly with the shorter arms.
Add: Here is how it looks on the arm with loop bands of different colours:
The wearability is not only due to the objective measured thickness of the case but also due to the ‘conic’ shapes of the case and its protrusion.
and the same with some quick helper lines, to better see the profile:
So it looks and feels (even) thinner on the arm than the measurements says. I guess a uniform 4-5mm ‘coin’ would look much the same placed on the arm (Slightly larger than a £5 coin).
You need to have REALLY tight cuffs on your shirt or wear a very tight sweater for it to hang on the T8, note how they even slanted the top edge of the frame, so there are only 3mm for the garment to get caught at.
In general protrusions on say a phone is a PEST, as they usually make the phone wobble on a desk. But on a smartwatch a protrusion is an advantage! The reason is that a flat watch would need to be mounted much more tight to get a good sensor-skin contact, than one with a small protrusion. (think of standing on flat feet versus on your toes)
Obviously the protrusion should not be so wide/deep that the case edges no longer reaches the arm, as this would make a ‘trap’ to catch a shirt sleeve.
The small crown is nicely designed like a classic watch crown, but though it do rotate, it is just a push button, and the design merely made to make it look like a classic watch. (BTW the blue centre you see on it in some images above is a protective foil I overlooked…)
The weight of the watch without band is 24g, with the 2mm Milanese band 62g, and with a third party 1.6mm Milanese loop band 53g (The similar numbers for a “Huawei Watch Fit New” (“HWFN” below) are 20g and 47g with a 1.7mm Milanese loop band, so quite close, considering that the HWFN is plastic and the display area of the T8 is 11% larger – 7.7 vs 8.6 cm²)
Despite being so thin, they still managed to squeeze in a vibration-unit powerful enough to wake me up, I had not dare to hope for that.
As can be seen above the T8 got three ‘windows’, It seems to be two emitters of various colours on both sides of a sensor.
Here an extra image, (click to enhance):
And a crop from the disassembled one:
When the T8 offers blood pressure measurements with optics only, I really would like to know how this can be done with any accuracy??
I only have a GUESS on what they do, I assume they ‘plot’ the intensity/colour of the response signal from the sensor, and then look at the slope of the incline & decline of the change, and then mean this over a number of pulse signals, possibly after removing outliers.
The heart rate seems to be measured as the distance between each individual stroke (and not by counting the number of strokes over a period), and you can get the live number in the app. (I assume that what they register as measurement is also done after some filtering and mean over a short period – but again just guessing)
A little on the mean thickness
As this watch has an unusual (an I believe very well thought through) profile, it is a little hard to talk about the thickness. It would not be fair to take the thinnest 4mm, nor would it be fair to only see at the rather small protrusion and say 7.8mm, as it actually is important that it DO protrude. One could take the largest flat surface and say 6.9mm. But I think a more fair way to do it would be to find the volume (less crown and band-arms) and divide with the area, and thus get a mean thickness.
The profile-thickness as a function of the radius (r) can be described as
r≤9.3mm : 7.8mm
9.3mm<r≤10.0mm : linear from 7.8 to 6.9mm, α=-1.3
10.0mm<r≤17.0mm : 6.9mm
17.0mm<r≤21.5mm : linear from 6.9 to 4.0mm, α=-0.64
21.5mm<r : 0
Integrating that over the area, gives a volume of 9.463cm³, and the area is obviously 14.52 cm² [=ᴨ (2.15cm)²], and dividing the two gives us the mean: 6.5mm.
A few extra spec-infos
The water protection rating is IP67.
CPU/Main chip: RTL8762.
Heart rate sensor: VC32S.
Bluetooth: BLE 5.0
Vibrational motor: Non-SMD motor 820 (Nice that it’s NOT mounted on the main board, so vibrations can not destroy its solderings) – see disassembly section later.
Android min v4.4, Ios min v9.0
Neither NFC nor GPS (though unsurprisingly offers to use the location from the phone).
I see no mentioning on the ‘crystal’, so I guess it is
unlikely to be Corning Gorilla (or similar). It does feel like glass and not plastic.
The glass disc is ever so slightly lower than the bezel (about a hairs width), so that could protect it a tiny bit, e.g. if placed up side down on a table with some fine but sharp dust.
No scratches or the like after the first four months, so points at something harder than just ordinary glass, unless I have been extremely lucky – but it has been the season of long sleeves, so could be mere luck. After five months, no scratches, and tried to scratch one with a knife and a screwdriver, with NO marks!, so clearly not just ordinary glass. ADD: Tested on a defective unit (bad battery): A Mohr 6 stone leaves no marks, a Mohr 7 can with substantial pressure, Mohr 8 fairly easily, so hardened glass, definitely not sapphire (Mohr 9). So consistent with the Mohr 6.8 of e.g. Gorilla Glass.
The timer max is 24h (less one second).
The stop watch allows for 10 lap times.
Notifications can be wiped individually, or a s a whole.
The watch keeps up to a weeks data if not connected to a phone. (well 6 whole day, and then depending on the time of day, as it wipes days as a whole for reuse)
High wearability in contrast to others…
Believe it or not the below left image is actually a crop from an advertising image for a “Huawei Watch Fit 2”, not a scare campaign!! (taken from here)
The Fit2 is far by the only one out there with such poor wearability, but I think the difference is quite striking. (Huawei´s previous versions are substantially better than the Fit2 here, see e.g. below or this post).
The Fit2 has a 6% larger display than the T8 though (9.1 vs 8.6 cm²), and the case area is also 6% larger (15.4 vs 14.5 cm²).
Of course my arm is a bit wider, but that far from explains the whole difference in wearability. The 10.8mm vs 6.9mm (both ex protrusion) makes a huge difference, as does the more flat back of the Fit2. If I tighten the T8 band, the crown sinks ‘into’ the arm.
For further compare I just took a picture with their better designed predecessor “Huawei Watch Fit New” and one with my beloved Omega Seamaster Polaris
So the T8 looks much more like a real elegant watch on the arm, than yet another pill-box-on-a-string or diver’s watch lookalike, and might actually have a chance of replacing the Polaris as my standard watch.
Usually the manufacturers go to great length to not show how poor wearability their devices offer – so kudos to Huawei for being honest about the Fit2…
…And really odd that the T8 advertisement images do not show how thin it is worn on the arm. Maybe it is a matter of not dissing the long list of other smart watches they have in their portfolio, that has just as low wearability as any other brand.
Software & Firmware
The software used is “Qwatch Pro” for Android. And in general it works OK, but certainly with room for improvements. Worst of is that IF it is not currently connected to your phone (App killed, phone off, out of BT reach…) any other phone with the software can connect to the watch, interact with it, and disconnect, without I would ever notice!!! (well it do vibrate shortly when a new connection is made, But I#m NOT requested to confirm the connection).
As they offer (NOT required!) to make a user account it would be fairly easy to link the ID of the device with the account, and do a lookup on any connection attempts, and deny if not the same account – a simple solution, without the need of correcting the T8-firmware. (tried to send as a feedback – we will see if it will be fixed)
The lack of connect-confirmation is also seen on other smart watches, also using other software, so (unfortunately) by far limited to this one…
The device offers measurements of “Heart Rate”, “SpO2”, “Blood Pressure” and Sleep. Plus some sports and period-cycle stuff, that is both outside my scope.
It does not only (like many other) offer ad hoc measurements of the HR/SpO2/BP, but also offers automatic measurements of the HR every 5min, and SpO2 and BP hourly. Plus detection of Sleep-state (Awake/Light/Deep), though it does not separate out the REM-phase as e.g. the Huawei ones does.
And the measurements seems to align fairly well with what the HWFN reports, But I do believe the HWFN is more accurate..
The software offers to nag you on “Sedentary” and “Drinking water”, BUT you can turn both off! It also allows you to set your daily goals so high, that you don’t risk being disturbed by reaching it – nor nagged when you do not (e.g. you can set the daily distance to 100km, exercise time 11.5h etc)
The software offers
132 dials (155 about four weeks later) to choose from. The watch supports four faces, where one is fixed, one is digital only (with user selectable background – see below), and merely two are user selectable. (click to see detailed collage)
Some are nice and neutral e.g these (the white balance of the photos is a bit off though)
(the first with the original band, the second with a loop band, with the less elegant band end above 12 o’clock)
Here a dump from the configuration for the user selectable background:
Nice detail that you can tone down the image, if you have troubles finding a suitable contrasting colour.
A silly detail in the firmware (And this is not just the T8, many others e.g. the HWFN has the same issue) is that there seems to be missing a setting for the wear direction, that is you can not select to have the display logically rotated so the crown would get to the left, if you should prefer that… As this is only a button and not a real active crown (AFAIK), the issue is mostly cosmetic, but why not give people the choice?
The T8 also offers AOD (Always-on-display), where it shows a clean watch-face (independent of what you have uploaded/selected).
Can’t hardly get much more classic watch than that 😀
Though I would have preferred if hands and markers were ‘matching’ the case ‘gold’/’silver’.
It would be really cool if they offered something (even) more minimalistic (also) :
Apart from looking cool, this would also be better for the AMOLED, than having the same LEDs on, all the time (that is why I removed the hour markers and cut the centre away also in the mock-up)
I experimented with AOD a bit (see later on battery). You can select a time window for when AOD shall be active, strangely I see no option for coupling with the existing automatic sleep-detection.(I tested over night, and it is not there by default).
A clever little detail: Like so many other smart watches, the T8 offers the feature of raise-to-wake, and a setting for how long the display should stay on after last interaction. BUT they extended this with the neat feature that if you touch the display again within 3s after the screen has gone off, it wakes again. This feature is really nifty if you have been interacting with the watch, and for some reason paused so long that the screen goes off. (Obviously you can also just press the button or twist your wrist)
If you reacitivate it within 10s of the display going off within some deep menu, you are returned to the place you were. Longer than that and you will start at the watch-face.
Though you can turn the raise-to-wake off/on quite easily, it would be handy with a setting for on, but display only, where you could set the touch passive until button-press. That could be nice if you were doing something that might trigger the raise-to-wake inadvertently. But I guess the AOD On with raise-to-wake Off, could do the trick here.
The T8 should also be praised for its quite fast synchronization of its collected data, data from the last 24h is transferred within about 3-4s, it takes much much much longer on the Huawei Watch Fit, usually over 30s. Also the transfer of new watch faces is reasonably fast. It came with 1.00.22_221012 firmware, and have not been offered any newer firmware upgrade (yet) – The R18 at the bottom did have a couple of updates, and they were transferred fast too. I do not know if the transfer-speed is high, or they only need to transfer small amounts (perhaps using compression)?
ADD I bought a handful of T8s as gifts, and some have a slightly newer firmware 1.00.23_221215 (I guess the last six digits is the date?), But It has not been offered as an update.
Battery and stamina (updated)
The battery is 185mAh (I assume 3.6V).
I measured a full charge from 0% to 100% on two watches and they charged at a completely consistent rate of 1%/minute, so 1h 40m for 0-100% charge. It charges with 5V, and starts pulling with just 125mA, and falls as in this table
Note that it still pulls 38 mA after “100%” is reached, leaving it attached for an additional 15 min, it falls to 10mA and then drops to zero) So leaving it attached for 2h, will charge the battery as much as possible. The weird ‘beyond 100%’, also explains why it stays at “100%” for over a day, the first charge I did below (might not have been 15m over) it stayed at “100%” for over 24h, it had ‘dropped’ to 99% after 36h.
(Add: I charged mine to its max Feb 9, and it stayed at displaying 100% until 99% Feb 13!!)
The stamina is an impressive 3-4 weeks ! with my usage pattern. Now that was a pleasant surprise!!! 😀
Especially as the advertisement numbers are “5-7 days“.
The blue is the T8. (The red is a HWFN)
Note that I on the T8 experimented with AOD and other settings, including watch-faces after 4½ days, and that pulled it from 85% to 82% within an hour, so AOD is (as expected) a costly feature when activated. (see a bit further down)
I have registered the remaining percentage at about 09 and 21 (almost) every day starting fully charged 2022-12-27 21:00. And still 23% remaining capacity after three whole weeks is really impressive! Combining the numbers, you will need to charge about half an hour per week.
The HWFN (red curve) had a few charges in between, but has been recorded also since 2023-01-09 09:00. And the HWFN used the same power (from 100 to 22%) in 8 days as the T8 did in 21½ day. Percentages are estimates, so would be more surprising if it was strictly linear. But both are fairly linear, enough to be able to predict the behaviour reasonably well. But don’t expect that the lines can be sensibly extended all the way to zero… Usually for devices using LiIon batteries levels below 20% shall be interpreted as “charge as soon as possible”… So I stopped the experiment here, was just checking if it could really last over three weeks, as extrapolating from the first week suggested. And it did – even with a margin of likely several days.
I assume the much longer than expected stamina I get is due to:
‘ve deselected push of notifications to the T8 The app on my phone is killed after each usage (by Greenify), so no ‘constant’ communication.
- I do not use the T8 for all the sport-stuff that many likely would.
- Apart from all the automatic measurements in the background, I don’t interact much with it during the day, except raising to check the time.
- In the test period I synchronized the watch and app twice a day, checking the percentage after. (Both the T8 and the HWFN)
- It has been on the arm (almost) all the time (less bath), and covered with the sleeve of a fleece during the day, and by a duvet at night, so roughly constant temperature, I would guess about 30°C
ADD 20230125: I tried to use it with notification and BT communication, and interacted with the watch at the least 20 times and the app a handful of times including testing several changes of watch-faces. I even tried out some sports modes for some minutes And yet it only went down one percent point from 99% to 98% in 24h.
So depending on your usage pattern, you are likely to not get the same long stamina – I mean they do advertise it as “5-7 days”. Yet it with my usage pattern ends over 3 weeks, and the T8 clearly has substantially better stamina than both the Huawei Watch Fit New, and the Huawei Band 6, that advertises “7-10 days” respectively “up to 2 weeks” (both these advertising estimates matches the actual stamina I usually get/got from them, down to about 20% , with similar usage pattern as the T8).
After 4 hours it was still at 100%, and after 6h 98%, after 12h 78% so though the “battery runtime” might be “massively decreased” it is not to an extent I would categorise as “extreme power consumption“.
Maybe the consumption is reduced from “Extremely lean” to “lean”, we are clearly still talking stamina in days not hours, But it might well be only a few days.
If we select it to be on say between 7 and 22, that would most likely give 2-3 days stamina in contrast to the 3 weeks, with AOD turned Off.
But even the 2-3 days is a very respective stamina for such a thin watch with AOD activated, IMHO.
That AOD with the face offered might not be such a good idea for the AMOLED display is quite another story, see above, especially the hour markers being constantly on seems unwise. So it is a feature I expect to rarely use beyond initial tests. Perhaps with Raise-to-wake turned Off while doing some manual labour though – or for social events having it look more like a proper watch, than just a black disc.
I Disassembled a defective unit. (broke cables doing so)
Here some pictures. (as usual click to enlarge).
I disassembled it using a heat gun heating the whole thing, removed the foil with windows for the optical sensor/emitters, and then pushed the sensor-board, battery and display out from the bottom. This brutal way I broke the ribbon cable for the sensor-board, obviously I ought to have used a suction cup, pulling the display off, but the one I had was too big for the display…
- Number one on the list is that connections from a new phone/tablet required a confirmation on the watch
- A more AMOLED friendly AOD display, The hour-markers and centre could be made as a fixed background we could choose on/off. (see mock-up above)
- It would be awesome if the above AOD screen came with hands in ‘gold’ or ‘silver’ matching the case. (perhaps as option)
- The AOD should hook onto the existing sleep detection and turn AOD off during sleep.
- The timer ends with a single short vibration, with no repetition, that could easily be missed. A more persistent pattern (e.g. like the alarm) would be nice.
- A way to turn off the display when the timer is counting down, important if it is not just a few minutes. Could be done by turning it into a one-time alarm, when the display is selected off. To simplify, only allow if more than 15 minutes left, and round to nearest minutes, so existing alarm system with integral minutes can be used.
(We can select up to 23h 59m and 59s – And I highly doubt anyone would plan to watch that counting down…)
Wishes for next model
It would be great if they for the next version could manage to squeeze in a proximity sensor to turn the display off when covered with say a sleeve or duvet. Would be awesome combined with AOD.
And a little extra memory, so it could hold more than 2 user selectable watch-faces would be nice too. Though in all fairness it is quite fast (10s) to fetch another one from the app, and after playing around initially in reality I keep coming back to the same two faces as my preferred ones anyway.
If possible a larger screen in same body – that is less bezels – would be great.
I’m not a big fan of the attachments arms being of equal width, would prefer if they ‘integrated’ into the case like the R18 (or any classical watch).
I would not mind if these attachment arms were shortened say 0.5-0.9mm. It would still make it possible to use a loop band directly around a pin.
Both would make the whole thing look less fragile.
The arms are shortened in the 2023 version. 🙂
They also got a model R18, that is the 2020 predecessor.
Sold as “2020 Smartch 7.3mm Super Slim Smart Watch Women” here, the “R18” is on the box.
Slightly more compact and 1mm ‘thicker’ – still thinner than anything else I found out there!
It is 8.7mm including the ø18mm protrusion, and 8.1mm outside that. (Some advertising falsely claims 7.3mm thick)
The diameter is 42.2mm and the length is 47.6mm including the arms.
The R18 case looks more ‘Classic’ than the 2022 T8 that got longer arms than what is ‘common’, the 2023 T8 has standard length arms, just like the R18.
The display is 1.1″ 240x240pixels, IPS (218PPI).
Why they made the 3mm bezel-ring pink and not ‘gold’ is beyond me. (It is more pregnant on the ‘silver’ model, but works OK on the ‘gold’ one), here advertising renders (with exaggerated display size):
Video from Azhuo with real images here.
Real image taken from this video
My guess for the reasoning behind the ‘pink’ ring, is to split the 6mm bezel-ring under the glass into two rings (2.5 and 3.5mm).
The display coverage is 44% of edge to edge, and 49% of the glass surface, but 64% of the area within the pink ring, so a clever trick. 🙂
Actually the glass disc seems to be the same 40mm as on the T8, so less metal bezels on the R18.
The R18 also uses standard 20mm bands, and came with the exact same band as the T8.
It is the same Qwatch Pro software that is used as for the T8, but the R18 offers four user selectable dials among 106 (versus the mere two for the T8) – which makes sense if the allocated memory is the same, with the over twice as many pixels on the 40% larger display of the T8 (9:4).
The battery is 150mAh. I do not know what the stamina is, but would expect it to be shorter than the T8, due to 19% smaller battery (and older chips).
I found these specs
|5 days normally use;
30 days standby
But as the T8 is rated “5-7 days Normal mode” and “30 days Battery life” officially, and actually is 3-4 weeks(!) with my usage pattern, I would expect the R18 to last well beyond a week – depending on using patterns of course, but even five days is tolerable, as it will easily last an extended weekend out, without the need of bringing the cable.
R18 usage feedback
I got some feedback from the one that got the R18, and after a few days it is bad news:
- The alarm does not work as it is supposed to.
- Some notifications from an Iphone are missed.
(I’ve ordered her a T8 instead, and keep my fingers crossed that it will give her a better experience, despite having slightly larger footprint)
Pebble Time Round…
The ONLY previously existing smartwatch looking smart like a watch was the ancient 2015 Pebble Time Round! Below is an image taken from here.
That was 7.5mm thick, ø38.5mm, had a flat back, a 1.0″ e-ink display with a huge bezel ring around the display, and no sensors at all, except a microphone. It came with either arms for 14 or 20mm bands. Despite the e-ink, it only had two days of stamina.
Unfortunately (AFAIK) nothing else comparable exists, except the R18 and T8 that is!