MIO Slice HR Activity Tracker
The MIO Slice is a stylish and small heart rate and activity monitor. Its main feature is PAI is Personal Activity Intelligence, a scientifically-validated metric showing how much activity you need to do to stay healthy.
- PAI is Personal Activity Intelligence, a scientifically-validated metric showing how much activity you need to do to stay healthy.
- Get heart rate intensity feedback with PAI technology, tracking all activities even those that don’t involve steps.
- Accurate continuous heart rate tracking, 24/7. Also tracks steps, distance, calories burned and sleep as well as displays smartphone notifications.
- Compatible with select smartphones: iOS 9.0 and above (iPhone 5S or newer) and Android 5.0 and above (Google Nexus 5, 5x, 6, 6p; Samsung Galaxy S5, S6, S7, Note 5).
- For any questions or product support, please contact Mio Customer Service at 1-877-770-1116: Mon-Fri, 9am to 5pm PST.
Steve Rogers –
There is a lot good about the Slice. I think the basic idea is sound – steps are very superficial and don’t really measure anything. Heart rate is a much better indicator if you want to measure exercise. The device is generally OK – it’s reasonably comfortable. It is able to read your heart rate. It sends the data to your phone, where an app gives you a score. But there is a lot of detail in making that practical. It seems like everything nowadays is run like a kickstarter project – get something out the door, then work out the details later. The Slice seems to follow this pattern. For example: – why is the button so huge? You’d think from the shape that it is a rocker switch, but it isn’t. Because it’s so huge, if your press is a little offset from the center, it will click when pressed, but nothing happens. That big ridge on the button that seems to be saying “press me here” is a decoy. If you press there, nothing happens. It’s really annoying to figure that out in the first minute or two of use during pairing and firmware update. – the firmware update is glitchy. The first unit I had bricked itself during firmware update. The second one failed during the first attempt, but succeeded on the second try. Yes, firmware update is hard. But it needs to be reliable if you’re going to let devices out with old firmware so that firmware update is 2nd thing the user has to do when setting up the device. – the app is so minimally featured that it’s more like a proof of concept than an actual fitness application. It collects the data in a highly compressed bar chart which would be cool as an overview – but that’s it. You get your magic PAI score, but no real view of the data. It’s not clear whether the data stays entirely on the phone. During sync with the device it says, “syncing with server”, but you have no visibility into that. It might be cool from a privacy perspective if the data stayed only on the phone, but there’s no way I can find to access the data. You can’t export it to the Apple Health Kit, or upload it anywhere (e.g., the way Garmin devices work with the Garmin Connect web site). As far as I can tell, your data is dead-ended in this app, and there is no way to get it out, or back it up. – the PAI score seems like a really good idea. Steps are superficial as a metric, and those other trackers can’t even count that accurately. But the PAI score seems somewhat arbitrary. For example, I get 25 points for walking around in the grocery store for 30 minutes. 50 points for inline speed skating 18 miles in a little over an hour. I understand the points are just an arbitrary number. It’s all just for motivation anyway. But the points need to make just a little bit of sense, otherwise it’s not motivating. When the points don’t make sense, you feel like you’re being cheated out of something. Maybe the points will level out over time with more use. – Sleep tracking is pretty much non-existent. It gives you a highly compressed chart similar to the one for workouts, with light sleep, deep sleep, and awake totals. It seems like the HR display uses your “resting heart rate” as the minimum value, and won’t show anything below that. That’s a bad idea, because nighttime heart rate often goes well below that. There’s a well known dip upon going to sleep, which is part of the HR you want to see for sleep tracking, but the chart cuts that off. This is just plain dumb. The chart floor should be the lowest data value, not “resting heart rate”. [update: It seems like the device keeps updating resting heart rate over time to the lowest value it has observed (though it’s hard to tell, because you can’t readily confirm any minimum value). This is a bad idea because “resting heart rate” normally refers to your awake daytime minimum. The nighttime minimum can be considerably lower than that, but you don’t want to treat that as “resting heart rate” for exercise purposes.] – I’m getting about one day of use out of it between charges. I’ve subsequently turned off all vibration and notifications, and will try never activating the display to see if I can get two days out of it. [update: after turning all the buzzing and alerting off, and not fiddling with it unnecessarily, I burned 20% of the charge over a day, so you should be able to get 4-5 days of use with minimal use. Probably 1 day if you turn all the alerting features on.] – The physical unit seems solid and comfortable. After 3 months use, the screen is still unscratched, although I’ve accidentally bonked it a few times. It’s pretty comfortable, pretty much like it’s not even there. The strap and the unit itself seem to be holding up perfectly. I get it wet almost daily, and no issues so far.One Month Update: after a month of use, I’m still running PAI scores around 230-280. Supposedly, it adapts to your level of fitness, so that 100 becomes the right number for you, and it becomes harder to rack up big PAI scores. So far, I’m not seeing that. Wearing it has become fairly ordinary. I hardly notice it anymore.Three Month Update: about once every 2-3 weeks, the phone app hangs on the purple “Syncing with Server” screen, and then crashes. After that happens, it won’t do anything except show that screen, then crash. The only way I’ve found to get around this is to delete the app and re-install it. Then you lose at least some of your data. This is fairly annoying. Hopefully it will be fixed soon.In Summary: If you want all-day HR tracking, this seems to be the way to go. But there is a lot of room for improvement. Hopefully there will be future updates to the PAI app that let the data out of jail, and make it more generally useful.
This product was very comfortable and secure to wear. The display was bright and very readable. I also liked the associated app (Mio PAI 2.0 for SLICE). The device inititialy synced quickly with the app and the activity recording was fine. I had gone outside to do some yard work (leaving my phone in the house) and when I came back in the app would not reconnect to the device. The app would see the device but would error out when it attempted to connect. After several attempts it did manage to re-connect and re-sync. This happened twice more later in the day. Overnight was fine and after I had put the device on the charger it would not reconnect again. I did work with the Mio support folks. I did online chat with their support folks and it was a good interaction. They had me uninstall and re-install the app, clear phone cache and do a factory reset on the device (which wipes out any data on the device). Though the app saw the device it kept erring out when attemping the connection. In the end they were unable to resolve the issue. They were at a loss to explain what was going on. While they admitted that they obviously can’t test with every phone their requirements for my device was only listed as needing Android 5.0 and above.I liked this device. It was well made and the associated app was fine. I just wish the experience using it had been more consistant.I had to return the item.
I had my eye on this for a while – I was particularly interested in the “pai” metric as a way of encouraging sufficiently rigorous workouts throughout the week. But when it was released many of the reviews I saw were fairly negative: poor accuracy in measuring heart rate and sleep patterns etc.My curiosity got the better of me and I took the plunge. I’ve had it for a few weeks now and I have to say I’m pleased with it.The Pros:The pai metric really is effective. 10,000 steps are easy to achieve – but keeping your weekly pai score above 100 takes some genuine effort and can become a bit of an addiction. Three decent workouts a week is just enough to keep me over the 100 point threshold, especially if I throw in a few quick hill walks.The accuracy of the device is excellent. I compared it to my Wahoo chest band and it was near identical. Ignore the negative reviews on accuracy. Same with sleep patterns – sleep tracking is at least as good as my wife’s fitbit.The Cons:The strap is too small. I don’t have giant wrists and I have a large size which I can only just get on.The screen is very difficult to see in daylight. Not a big issue for me since most of my workouts are indoors, but if you wanted a quick check while out on a jog you are unlikely to see a thing.I had some issues syncing with the server, at least initially. I had to delete and reinstall the app a couple of times to get anywhere. It seems better now, but syncing can still take too long in my view.All told I’m happy with it. The pai metric really does motivate me and the accuracy is superb. My wife will be getting one soon so we can introduce a bit of competition – who can get the most pai points! Sad I know, especially since I’m almost certain to lose…
I really liked it, except I could not get it to sync with my app and most of the time I didn’t show a heart beat. I read this is first year. I will wait and see it MIO gets the bugs out and try again. I returned it.
J P McBride –
Doesn’t keep historical data for more than a week. The company claims to be working on it but that’s a bit frustrating – the app can’t keep the data either. Otherwise good product. The fact it’s waterproof is a major plus!!
I purchased this tracker at a heavily reduced price as an alternative to the Mio Link that I have been using for a few years. I am a competitive masters athlete (Septuagenerian) and was drawn by the PAI calculation method for activity; this is based on the raising of HR and does seem to work well. I like being reminded everyday what my score is based on the previous seven days and especially when it shows no PAI on a recovery day.I have to say that the band took some getting used to – the clasp needs ‘wearing in’ as it is very stiff to begin with but after a month’s daily wear it is fine. The display dulls dramatically in sunlight so is not much use if you want to look at whilst out exercising; this does not unduly concern me as I link it to the i-smooth run app when training but not very useful if you want to know the time of day!I like the sleep tracking aspect and again it seems to be quite accurate.
Tony B. –
I was looking for a comfortable waterproof activity tracker and the Mio Slice seemed to be just what I was looking for. I have found it to be more comfortable than I had expected and it has been very accurate. I had a Nike fuel band for years and was looking for a replacement and when I came across the Slice PAI concept I felt I may had found exactly what I was looking for. I’m kind of surprised by the number of fairly negative comments but I suppose it depends on what you are expecting. To reach the weekly PAI goal of 100 you need to have a fairly serious daily workout. For instance I ran a mile and a half down a steep mountain road then walked back up at a quick pace and got only 3 PAI points. High rate cardio is key… I box two days a week for cardio and go to a boot camp style circuit training three days a week and find a 45 min session of either will get between 12 and 26 PAI points. They key factor for PAI points seems to be sustaining a high level heartrate over any other factor.Pros so far: Comfortable, battery life has been good (four days or so) and charges quickly, very accurate especially heart rate, waterproof (I have swam with it all this week and thought it would not track swim workouts well but it has). It’s also inexpensive as I got mine via an Amazon flash sale for $99.Cons: The slice app needs work. The app will not sync the device to my Motorola android phone (luckily I have an iPad and it syncs without a issue to that. It seems to have an issue tracking sleep as it will at times stop tracking sleep well before I wake up. I believe the app only tracks the past 7 days of activity which is understandable for the PAI points as it is a 7 day average however it does not seem to store your history of sleep, steps, cumulative PAI points, etc which would be nice to see as you progress.Overall it’s what I was looking for however if the app was improved I could see it becoming much more popular and user friendly.
It wouldn’t transmit heart or sleep data to the phone app, even after uninstalling and reinstalling several times. It was taking 3-5 minutes for the heart rate monitor to start to record during exercise. Overall, it was too much hassle to use and had too many faults. I think everyone just wants something efficient and easy to use when exercising. With this, in the time I had it, I spent as much time faffing around trying to get it to work rather than exercising. PAI is a good idea though, and if it can be implemented in another hardware platform, it will be good. I returned it within a few days, when it became obvious things weren’t going to improve
Ommund Øgård –
Failed after a couple of days. Comletely useless.
angela o –
Very pleased with my activity tracker. Easy to set up, I linked it to my iPad rather than phone, and it gives me a target to aim for each day, needing to achieve a score of 100each week.. It also tracks calories burnt, heart rate, steps, distance walked per day. The app breaks it all down for you to look at your daily totals. I found the sleep monitor useful, identifying amount of deep sleep and light sleep achieved each night. Glad I bought it.
Rich H. –
I bought this as it had an ANT+ protocol so that I could easily link it to Zwift software but in the end it was far more reliable connecting via Bluetooth so as an ANT+ device there was no real point.If the review ended here then it probably would have been a three or four star review, unfortunately after only two months the unit no longer charges and is outside the Amazon return window.Since Mio have stopped making and supporting wearable devices it’s probably better to avoid buying this item
Paul King –
Easy to use. Gives enough information for training. One big problem. No idea why, but it will lose Bluetooth connection. Won’t just reconnect as you would expect. Often needs a full reset. And repeat. Can take hours to resolve. Last time it happened I have up after an hour and just out it into a drawer where it now lives.