Activity Trackers: Mio Alpha Optical Heart Rate Monitor In-Depth Review (Bluetooth Smart/ANT+)

The Mio Alpha unit may represent the longest I’ve ever actually tested something before writing a review.  I initially got the chance to use a unit back in July for a quick test run as they were in the midst of their Kickstarter campaign.  Then in September, I received some early prototype units to try out.  Finally, in December I received the final production units.  During this time I’ve been collecting mounds of data.  Large stockpiles of it really.  I’ve got a crystal clear understanding of how well the product works, and where it falters.  So, how is it?  Well, read on to find out.

In doing so, I’ve got a pretty good grasp on how the unit works, as well as all the inside and out details.  In the case of the Alpha watch, I bought and paid for the Bluetooth Smart version, but Mio (company behind Alpha) also sent over two units (ANT+ and Bluetooth Smart) to test ahead of them being publically available.  These will be going back to them shortly.  Simple as that.  Sorta like hiking in wilderness trails – leave only footprints.

Lastly, at the end of the day keep in mind I’m just like any other regular triathlete out there. I write these reviews because I’m inherently a curious person with a technology background (my day job), and thus I try and be as complete as I can. But, if I’ve missed something or if you spot something that doesn’t quite jive – just let me know and I’ll be happy to get it all sorted out. Also, because the technology world constantly changes, I try and go back and update these reviews as new features and functionality are added – or if bugs are fixed.


There are actually two variants of the Mio Alpha unit, one is Bluetooth Smart enabled, and the other ANT+ enabled.  For those who bought-in via Kickstarter, they had the choice of either Bluetooth Smart, or ANT+.  However, these days, they are also selling the Bluetooth Smart variant.

That said, the packaging is identical on both.  With the only difference between the two being the tiny little sticker on the outside, and then the little logo on the back of the band itself.  Thus, I’m only going to unbox one, rather than just duplicate it twice.

Each unit comes in a small square box.  Slightly larger than a Rubik’s cube.


As I noted earlier, the only difference between the two variants from a visual standpoint is the little ANT+ or Bluetooth Smart logo.  In this case, both units are the color ‘Shadow’ (read: Black).


As you crack open the boxes you’ll find the heart rate watch staring back up at ya:


Here, a closer look:


Removing the inner watch box you’ll find a small packet of instructional stuffs, and the charger.


Here’s the charger:


And the whole kit unboxed:


The charger is actually pretty cool.  Probably one of the more ingenious chargers I’ve seen around.  The (albeit rather short) USB cable folds back onto the plastic unit itself, keepings things nice and tidy.


And to plug the USB cable in, you just pull it up.  It’ll twist around as you see fit, it’s just like any other cable.


Flipping it over, the unit features a small magnetic clip that holds it tightly to the watch:


Speaking of the underside, here’s what that looks like.  We’ll dive into it more in a section or two.


With that, we’ve got everything unboxed and ready to start using it.



Unit comparisons:

When looking at the size of the unit, it’s about the same as most wrist watches:


You can see this a bit more clearly when compared against the Polar RC3 GPS watch, and the Garmin FR610 GPS watch.  The Alpha is perhaps a touch bit longer in the watch face itself, but is about the same width and height.  Plus, some of that length in the face watch is actually the band portion.


Initial Setup:

Setup on the Mio Alpha is pretty straight forward and basic.  There’s not much to do really, beyond removing the sticker and setting the time.  So with that, remove the sticker:


Once you’ve removed the sticker, you’ll go ahead and turn on the unit by holding the right button down.


Upon startup it’ll show you the Mio logo:


Then, you can go ahead and set the local time.  The time isn’t actually used for anything beyond just telling you what time it is.


The reason the time isn’t used for anything is that the unit doesn’t record anything.  It’s just like a heart rate strap in that respect – it just displays your heart rate and transmits it.  And, beyond a basic timer that you can start/stop, there’s NO other functionality on the watch.  You turn it on, it transmits your HR and displays it, and then you turn it off and it shows you the current time.  End of story.

Mio Alpha Heart Rate Monitor Sports Watch

Alpha is the world's first strapless, continuous heart rate monitor you can wear on your wrist. It has been tested accurate even while you are running at performance speeds of up to 12mph (20km/h). ...

Made by: Mio,

A bit of background on the technology and the strap:

Unlike traditional heart rate straps, the Alpha isn’t placed around ones chest.  Instead, it measures heart rate at your wrist.  You can use either left or right wrist, it doesn’t really matter.  Whichever is most comfortable for you.

The unit uses an optical sensor to measure your pulse.  It does this by emitting a green light into your skin, which allows the unit to then more clearly read your pulse.  You can see the green light below:


Unlike other watches such as the Basis unit, this doesn’t measure any other attributes (such as skin temperature).  It only does heart rate.  But, it does it really darn well.  And in particular, it does it with a focus on athletics.  That’s an area that the Basis folks themselves will admit their unit isn’t focused on.  Their core area is 24×7 monitoring, rather than higher performance running (or really, any running).  You can see a photo I took of the Basis watch below.  As you can see, it looks relatively similar.  But of course, looks are deceiving.


Some of this come down to technology.  If you think about what’s going on, the sensor has to optically measure your heart rate while your running.  That running often includes significant jostling, bumping, and just in a general a non-smooth ride.  The technology is the Alpha is specifically optimized for that, whereas the Basis isn’t.  And, when it comes to the technology behind the sensor – it isn’t something that Alpha just plopped out one night.  In fact, the technology was exclusively licensed from Philips Medical (the company that makes hospital level stuff).  The ‘exclusive’ part means that Mio has full rights to the technology, and can sub-license it if they wish to other companies (i.e. they could sub-license the optical portion to Garmin, and Garmin could build it into a watch).

Which, brings me to my next point.  None of this optical technology is new.  In fact, hospitals have been using it for years.  Typically in devices like the one below.  What’s new is taking it into a functional sports watch form factor.  And by functional, I mean one that can work while you run.


When it comes to tightness, many folks presume it must be boa constrictor tight.  But I’ve found that usually isn’t the case.  I can get good solid readings in most cases without it being annoying tight.  Just snug, but not super-tight.  In fact, as you’ll see later on, I’ve worn it for some stretches up to 30 hours at a time gathering data, with no issues when it comes to the wrist.

(Side note for those curious about Basis:  As soon as a unit actually shows up on my doorstep, I’ll start using it for a review.  Note that comparing Basis to Alpha is like comparing a fighter jet to a business jet.  Yes, they both fly (optical HR), but one carries guns, missiles and bombs, and the other carries passengers and champagne.  Totally different purposes.  In the case of Alpha, it’s all about athletic HR without a heart rate strap.  Whereas Basis is all about 24×7 health monitoring beyond just heart rate…but not for athletics.)

Day to day usage:

As I noted above, the unit is pretty basic in that it only transmits your HR and displays it.  It doesn’t record it.  When you start to ask yourself what functionality the unit might have, the easiest way to obtain the answer is to ask yourself if the same functionality is found in a heart rate strap. Here, let me give you example:

Q: Does the unit record your distance?
A: Does a heart rate strap record your distance?  No.  Neither does Alpha.

Q: Does the unit display your location like GPS?
A: Does a heart rate strap display your location like distance?  No.  Neither does Alpha.

Q: Does the unit transmit your current heart rate?
A: Does a heart rate strap transmit your heart rate?  Yes.  So does Alpha.

Q: Does the unit record your heart rate for downloading later?
A: Does a heart rate strap record your heart rate for downloading later?  No*.  Neither does Alpha. (*Ok, one strap does, the Suunto Memory Belt).

Q: Will the Q&A continue like this?
A: No, I think my point has been made.

Make sense?  Good.

Of course, there are some exceptions to my tongue in cheek rule.

Now unlike a heart rate strap, you do have to turn this on.  To do so, simply hold the button on the right again for about 2 seconds, and it’ll start searching for your heart rate.  It’s best to ensure the unit is already snugly on your wrist before you begin the search process.


Once it’s found your heart rate, it’ll display your current heart rate value on the unit.  It’s at this point that the unit will start transmitting that value over ANT+ or Bluetooth Smart (depending on version you bought).  It will NOT start transmitting any value (zero, null or otherwise) until a heart rate is found.  Meaning, if you’re doing pairing, you’ll need to get a heart rate value first, then it will pair.  Zero or null doesn’t count.

From a pairing standpoint, the unit works exactly the same way as any ANT+ heart rate strap (if you bought the ANT+ version).  You’ll simply go into the ANT+ settings on the unit and then pair it.

And, when using a phone app, it also works the same way.  You’ll go into any Bluetooth Smart compatible app and dive into the pairing menu.  From there the unit will pair with the app.  Note that unlike ANT+, you cannot pair the Alpha to more than one Bluetooth Smart device concurrently.  Meaning, say you had a Motoactv (which has BT Smart connectivity),  you couldn’t pair it to both the Motoactv and your cell phone at once.  That’s because Bluetooth Smart has a 1:1 relationship, whereas ANT+ has a 1:Many relationship.  Again, not a big deal for most people (especially today with virtually no Bluetooth Smart watches out), but worthwhile mentioning.


You can see above that I’ve got it paired to my phone, and via the Wahoo Fitness app.  It’s the app I tend to use for just about everything.  The reason being that it’s free, uploads to a bunch of different services, and has tons of options for data export.  Oh, and it’s free.  And it ‘just works’.

Above, you can see the 90BPM coming from the Alpha.

Now, what’s important here is that I’ve seen a LOT of reviewers (for really big tech companies) not understand that Alpha is Bluetooth Smart. This means that your phone has to be Bluetooth Smart compatible, which means it has to have Bluetooth 4.0.  Today, that’s any iPhone from the 4s and later.  And some Android phones and some Windows Phones.

However – and this is the REALLY important part – you MUST ALSO have a Bluetooth Smart Heart Rate Strapcompatible app.  Let me repeat that again.  The app has to be specifically written to communicate with Bluetooth Smart.

And today the number of apps that do that is decidedly thin.  All of the biggies do, and most of them actually use the underlying Wahoo Fitness API’s to do so (developer stuffs).  So, as a general rule you can use the Wahoo Fitness site to lookup apps that are compatible with their Wahoo Blue HR strap.  If it works with the Blue HR strap, it’ll work with Alpha.

With me so far?

Ok, now, when it comes to the ANT+ variant, it’ll work with any ANT+ device you have that supports heart rate (heart rate device profile).  Which is pretty much every ANT+ watch/bike computer/hiking unit ever made on earth.  Garmin, Timex, Magellan, CycleOps, Mio, etc… Pretty much as long as you don’t have a Polar or Nike unit, you’re good to go.


When it comes to data display, you’ll see the two track fairly closely.  Usually within about 1-2 seconds of each other.  For example, in the below picture you can see that the data from my heart rate strap (fed into the FR610 on the left) is off by two beats from the Alpha unit.  Which one is correct?  Well, hard to know.


But, within 1-2 seconds they matched again (actually, the below was taken 1-2 seconds prior):


It’s worth pointing out that the unit doesn’t always find my heart rate on the first attempt.  I find that about 1:4 times I’ll have to tell it to ‘retry’ and have it search for my heart rate again.  I’ve found that if I then just move it slightly up my wrist (direction towards my elbow), perhaps 1-3cm (.5-1in) it usually solves it.  It’s not a huge deal, but it can be an annoyance at times.  On the flip side, once it does find it, I never have any issues with HR dropouts or spikes.  It just works…the entire run.

Now, that’s for me.  For The Girl, her wrists are too small, and it doesn’t work for her with any high intensity runs.  The reason being is that on lower-intensity runs the watch basically stays put.  But on higher intensity runs with more jostling, it ends up sliding down her arm towards her wrist (she has to start it up higher, because the band is too big).  Once it gets to her wrist though, the band is just far too big and it won’t get any useful HR values.  Below you can see a heart rate chart from one of her runs.


It’s probably hard to see what she’s doing, so let me slice it up a bit.  Then you can see why it’s so bad.  She’s doing mile repeats, but it’s really hard to see because the data is all over the map.  In reality, her pace is preset, and thus her heart rate would ‘stabilize’ within the first 45-75 seconds, and then slowly rise for the remainder of the interval.  You can see how earlier on in the run the HR values weren’t horribly off, but once she started the harder running sets, things got messy.


So while it ‘works’ up higher on her arm, it doesn’t stay there.  Simply put, the band is too big.  For reference, she’s 5’2” with tiny wrists.  Though, I don’t have a photo handy with her wrists and the watch on it (travelling at the moment).  I’ll try and get one added this week.

Update: Here are the photos on her wrist.  As you can see, even on the very tightest setting, there’s still a fairly significant gap on her wrists under the strap:



Unlike a traditional watch, you’ll need to have this placed below your coat in cold weather.  You can’t have it over the top of the coat as it won’t correctly pickup your heart rate through the fabric.


In looking at a few small features the unit has that a traditional HR strap doesn’t, I’ll first note that you can set a high and low heart rate alert.  This will give you a beeping alarm when you’re outside of the target range.  It’ll also change the LED color on the unit itself:


You can also start the timer that I mentioned above.  This gives you a simple total time display while the unit is running.


Additionally, at the end of a run, it’ll display the average HR value for your run, based on the last run that the timer was used.


Beyond that, it’s all about data transmission.

Mio Alpha Heart Rate Monitor Sports Watch

Alpha is the world's first strapless, continuous heart rate monitor you can wear on your wrist. It has been tested accurate even while you are running at performance speeds of up to 12mph (20km/h). ...

Made by: Mio,

Data comparison with normal HR straps:

I’ve used the Alpha indoors, outdoors, running, cycling, walking and just about everything in between.  From easy workouts to hard workouts, short intervals to long runs.  You name, I’ve done it.  And by and large, it works just fine and records generally accurate data.  I can mix and match data from either heart rate strap or Alpha, and there’s very little visible difference.  I see an occasional dropout (1-3 per run), but I don’t see the large spikes/drops that I often see on Garmin and other straps.  And typically, those spikes last for prolonged periods of times (i.e. 5-10 minutes or longer).  Versus a 1-second drop on the Alpha.

Of course, seeing is believing.  So, I’ve taken a ton of random runs below to show what it looks like. In the four examples below, the data was recorded in parallel between a Garmin unit (varied) using ANT+, and an iPhone connected to Bluetooth Smart.  There’s no data accuracy difference between ANT+ and Bluetooth Smart Alpha Models, so either model will act identically (I’ve done some casual trainer tests with two on at once).  It’s just the communications chip that’s different in the two units.

With that, let’s dive into the data.

Run #1: 80 Minute Run

Weather just about freezing level, dry and slightly breezy.

Figure 1: Garmin FR610 + standard Garmin HR strap (soft strap) (run file linked)


Standard Strap Avg HR: 157 bpm
Standard Strap Max HR: 174 bpm

Figure 2: Alpha Bluetooth Smart + Wahoo Fitness app (run file linked)


Alpha Avg HR: 157 bpm
Alpha Strap Max HR: 173 bpm

This follows pretty close, though I do see a few drops that aren’t visible on the Garmin file.  Beyond that, the units track fairly well against each other.

Run #2: Short Lunch Run (40 minutes at Z2 HR)

Just below freezing, sunny and dry.

Figure 1: Garmin FR610 + standard Garmin HR strap (soft strap) (run file linked)


Standard Strap Avg HR: 158 bpm
Standard Strap Max HR: 182 bpm

Figure 2: Alpha Bluetooth Smart + Wahoo Fitness app (run file linked)


Alpha Avg HR: 156 bpm
Alpha Strap Max HR: 164 bpm

This is probably one of the clearest example of the Alpha unit performing perfectly, compared to a typical HR strap doing initial spikes on a cold day.  Note all the wonkiness at the start with the chest strap, then compare it to the Alpha which mirrors what my HR would have been.  It was an easy run, just starting off easy and then holding a steady heart rate.

Run #3: Tempo Run (90 minute at two separate paces)

Weather about 40-45*F, overcast and dry.

Figure 1: Garmin FR610 + standard Garmin HR strap (soft strap) (run file linked)


Standard Strap Avg HR: 159 bpm
Standard Strap Max HR: 178 bpm

Figure 2: Alpha Bluetooth Smart + Wahoo Fitness app (run file linked)


In this case, you see that the Alpha did a better job getting the initial heart rate, whereas the Garmin strap lagged initially.  They both tracked quite well, though it looks like the Alpha had three drops towards the end.  Given I never stopped on my way back (out and back course), these seem a bit odd.

Alpha Avg HR: 159 bpm
Alpha Strap Max HR: 177 bpm

Run #4: Long Run (2hr 10 minutes)

Weather was generally miserable. Part snow, part rain, and running in a mix of snow/ice/slush, on and offroad.  Rather unpleasant.

Figure 1: Garmin FR610 + standard Garmin HR strap (soft strap) (run file linked)


Standard Strap Avg HR: 159 bpm
Standard Strap Max HR: 180 bpm

Figure 2: Alpha Bluetooth Smart + Wahoo Fitness app (run file linked)


Alpha Avg HR: 159 bpm
Alpha Strap Max HR: 177 bpm

In this example, you see a single errant point sorta towards the beginning a couple minutes in.  Things then track fairly well until the last couple minutes.  It’s unclear on why the Alpha became happy towards the last few minutes, as the other unit did fine.

Indoor Trainer Ride

This was just a 50 minute indoor trainer test.  I was doing a lot of other data gathering on power meters, so I decided to knock out two birds with one stone in this test.

Figure 1: Bluetooth Smart HR Strap (chest strap) paired to the Wahoo Fitness app (bike file linked)


Standard Strap Avg HR: 141 bpm
Standard Strap Max HR: 154 bpm

Figure 2: Alpha ANT+ variant paired to the Wahoo Fitness App (bike file linked)


Alpha Avg HR: 142 bpm
Alpha Strap Max HR: 155 bpm

In this sample, things look about as good as you’re going to get similarity-wise.  I see one tiny blip around the 5-minute marker with Alpha, but otherwise spot-on.

Randomness: Continuous HR monitoring (all day long)

Just to briefly point out that in addition to doing athletic monitoring, the unit works pretty darn well for doing continuous HR monitoring.  I wrote a fun post up on it back a couple months ago, showing some of the capabilities, where I recorded my heart rate from waking up to falling asleep – which included a full day trip for work on the high speed train and back.  Fun stuff.  You can dig into it here.


In addition to simple all day tracking of non-athletic endeavors, just today I also did one all-day tracking while skiing.  I paired the Alpha unit via ANT+ to the Garmin Fenix (which is ideal for longer term tests), and then went about my day.  In my case, I had stashed the Fenix in my backpack instead – since I didn’t really need/care to see it (just wanted tracking for later reference).


Worked great.  It’s funny to clearly see sitting on a chairlift versus powder skiing.



At the end of the day, I really like the Alpha from the standpoint of accuracy, functionality and ease of use.  As a product, it does execute on exactly what it claims to do.  No more, no less.  It transmits your heart rate via one of two standards, and displays it – and it does it really well, bug free, without a heart rate strap around your chest.

Where I’m conflicted is the price point.  At $200, it’s just really darn expensive for something that doesn’t even record data or otherwise have any functionality of even a basic $15 Target/Walmart watch.  Yes, I understand that it has multi-million dollar optical HR sensing technology.  But that isn’t any of the functionality commonly found in sports watches these days even half its price.

Thus, from my overall recommendation standpoint, it comes down to your own cost-basis determination.  Is the cost worth it to you?  For those that hate heart rate straps (be it for comfort, or due to spikes/dropouts), then this is probably worth the cost.  For those that don’t mind the heart rate strap, then I suspect you’ll see little value in this.

Long term, I think this technology is FAR more valuable licensed out to other companies.  For example, seeing this built into the back of a GPS sports watch.  Or perhaps, with the display removed entirely and just as a sleek heart rate watch wrist band that simply transmits (just like your heart rate chest strap, but for your wrist).

Please note that at this time, Mio is not offering the Alpha in the ANT+ variant.  ONLY folks who paid last July as part of the Kickstarter campaign and specifically ordered the ANT+ version will receive theirs.  Today, only the Bluetooth Smart version is available for purchase.


– Just works
– Both ANT+ and Bluetooth Smart versions made
– Data is generally quite accurate, even while running (hard)
– Battery is very solid, I can get about 30hrs of battery life before recharge
– Strap isn’t uncomfortable when worn, doesn’t need to be super-tight


– Unit is REALLY expensive
– Virtually no functionality on watch, just HR display
– Doesn’t record data, requires another device (only displays avg HR for last run)
– Band too large for small wrists

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Mio Alpha Heart Rate Monitor Sports Watch

Alpha is the world's first strapless, continuous heart rate monitor you can wear on your wrist. It has been tested accurate even while you are running at performance speeds of up to 12mph (20km/h). ...

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amazon Activity Trackers: Mio Alpha Optical Heart Rate Monitor In Depth Review (Bluetooth Smart/ANT+)
ok so as I like to begin any review here the short description:Is this is the HOLY grail of heart rate monitoring !!..... not really short this is a heart rate monitor (continues monitoring) that doesnt need a chest strap.. with BLE (Bluetooth 4.0) technology to connect to you Iphone (Iphone 4s, 5 etc..) Android users Hold off buying .. and read further uses (As they say) Multi-million dollar medical invention created by Philips (not sure about the make) and now its for the first time applied in the field of fitness and sports and it has its own patent registered for MIO or they state so reads the Heart rate through two bulbs on the bottom of the watch when in contact with your skin (hence the no chest strap option)but is it that great ..?.DESIGN:the watch is comfy , much like the Nike+ GPS watch it has holes on the strap that will hook into it to insure a nice fitwatch looks nice can be used in the regular day to day usage..Options:well it basically in option wise is very very close the to the FT1 polar options ... so that said will display :1) hear rate at moment in time2)continues reading3)timer counting how much you have been training4) it will give the average heart rate and time of the last session ONLY!!Plus it connects to BLE (Bluetooth 4.0) so you can have further options depending on your mobile or App installed ..Read more ›
December 30, 2013
Got this shortly after running my first full marathon. Even though I completed my run I wasn't satisfied with the results and looked into heartbeat monitors to better my performance. The MIO Alpha came top choice for me even for a blind first-buy. Most heart monitors out there require a strap to the chest or a constant touch of a sensor to get a reading. But with the Alpha the LED sensors give constant readings as well as a light indicator to show if you're in your targeted heart rate 'Zone'. Very convenient as well as more comfortable when you're focusing on running.Battery power is also quite satisfactory. After charging my Alpha to full capacity the power indicator stays full-bar even after constant use. I rarely need to recharge it thus. When I take it off, I also use the charger device as a cover for the sensor beneath the watch so that serves a double function at least for me.On the downside however, I'm not able to sync my Alpha to my Android smartphone via bluetooth. Apparently it only syncs with Apple iPhones. That's a real downer for me. Another con would be the inability to backlight, meaning unless I run in a well-lit place at night I'd only be able to see the LED zone indicator and not the readings. I understand though that this is still a first-gen technology, so I can't really expect that much yet.Overall a very much recommended product for those looking for their first HRMs. Some people would gripe about the price of the Alpha. Granted, it does take quite a bit off the pocket, but for a reliable device such as the Alpha I'd say it's worth every penny spent.
July 9, 2013
I've owned three heart rate monitors (Polar, Zephyr and Mio) over the last 12 years and this product is by far the least reliable. Granted, this is the first HRM that took a reading from my wrist rather than my chest, it goes to show that the technology just isn't quite there yet. Very disappointing as I was looking forward to ditching the dreaded chest strap. Although it provided very reliable readings, it was uncomfortable to wear and often had to be readjusted frequently under vigorous activities such as trail running.The problem with the Mio is its reading often drops slowly from 150+ to 80-90 over the course of roughly a minute even if my activity level (and heart rate) remain virtually static. Sometimes it will shoot back up instantly to where it should be (150) or it will just sit at the 80-90 BPM level forever... or until I reset the HRM and reconnect again. On the chart, it looks like I literally stopped in my tracks and I just sat there resting while my heart rate slowly dropped... very misleading. While resetting it usually prevents the HRM from replicating the same problem during the same training session, it has dropped off several times in one training session before. I've tried to tighten the strap (to the point where it became uncomfortable) but that didn't help. There is also no correlation to ambient temperature, relative humidity or activity type (e.g. cycling, vigorous trail/mountain running or just jogging) as it will do it under all weather conditions and activity types I've subjected the HRM to. I think it may have something to do with a flaw in the algorithm used and less to do with it not being able to track the blood flow itself. Whatever the problem is, it makes a potentially decent product a major failure.Read more ›
August 10, 2013
Activity Trackers: Mio Alpha Optical Heart Rate Monitor In-Depth Review (Bluetooth Smart/ANT+)
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