Aura Strap 2

Aura’s second gen smart Apple Watch strap is better

Aura Strap 2 for Apple Watch
(Image: © Michael Sawh)

TechRadar Verdict

The Aura Strap 2 now offers a better design than the first version and makes the measurement process slicker too. Without the added subscription service though, you’re getting a basic experience and there’s an argument that given the price of the strap, some of those paid features should be available without it.


  • +

    Improved design from the first Aura strap

  • +

    Now easier to take a measurement

  • +

    Doesn’t need to be charged


  • -

    Additional features requires subscription

  • -

    Feels expensive

  • -

    Fiddly to change straps

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Two minute review

The Aura Strap 2 is one of the few Apple Watch smart straps that exist today and like the first version, promises to deliver the kind of measurements you’d usually have to step on a smart scale to capture.

With Strap 2, Aura has changed the strap design and the method you take a measurement to monitor and analyze body composition and hydration levels. It now offers a subscription service, which unlocks additional features like monthly reports, workout plans and recommendations to keep you fighting fit, replacing the measurements taken by the Apple Watch itself.

The improved strap is welcomed and the way you take measurements has reduced the number of times it fails to register reading, though that can still happen. The Watch app is slick and well designed while the companion phone App and the compatibility with Apple HealthKit should make it a more attractive proposition for Apple Watch owners.

Beyond capturing some reliable measurements and breaking down things like fat, muscle, body water, protein and visceral fat, you’ll need to pay up for the subscription to gain potentially useful features like personalized recommendations and workout video plans, which feel like they should be included already.

If you’re happy to pay a quite sizable amount of money upfront for the strap and then add in the monthly or annual subscription then it could be a useful strap to have around your wrist. Ultimately though, it feels like a lot of money for something that will have niche appeal and means you have to ditch your fave Watch strap for life with this silicone one. 

Aura Strap 2: Price and availability

 The Aura Strap 2 is available from the Aura Devices website for $150 which is $50 more expensive than what you can pick up the first Aura Strap. If you’re willing to subscribe to the Aura Plus service, you’ll need to either pay $9.99 a month or $79.99 a year. 

Aura Strap 2 for Apple Watch

(Image credit: Michael Sawh)

Aura Strap 2: Design and features

  • Feels comfortable to wear
  • Unobtrusive sensors
  • Changing, adding or removing strap is a pain

Design score: 3/5

Like the first Aura Strap, the second iteration looks mostly like a normal Apple Watch strap and connects with the same lug design, but in the middle, you have a pair of medical steel electrodes that sit on either side of the strap, which do contain nickel.

Aura has switched from the softer nylon material strap it used previously for a silicone one and it’s also including additional sized straps in the box to make sure you get a good fit. Getting those straps in place, however, is tricky business. You had to take out screws on the first strap, so the process has improved, but it’s still not great.

There’s a guitar pick-shaped piece of plastic included that you use to open up the casing housing the electrodes where you’ll also release the replaceable coin cell battery that’s powering the smart strap and should give you a good six months of battery life depending on how regularly you use it.

Changing those straps is frustratingly fiddly to do and took us a fair while to line up a new strap inside of the casing to clip it back in place. It felt as if it would be very easy to break that case, which would effectively leave you having to buy a new one.

Once you get a strap that works, it’s as easy as clipping into place a standard Apple Watch strap. The positioning of the electrodes means getting this strap off has to be done by pulling it over your wrist, which can be a pain to do if you have big hands to stretch it over.

It definitely sits more comfortably than the first strap and is noticeably slimmer and lighter too, which is good to see. We used it with an Apple Watch Series 7, but this is something that will work as far back as the Apple Watch Series 3.

On the whole, the design changes are welcomed. It definitely feels like a better strap to wear than the first version and it’s good to see it’s one you can keep on during swims and showers as long as you don’t go deeper than 50 meters. Swapping the straps is still fiddly though and the build quality of the casing holding the electrodes in place feels a bit cheap.

Aura Strap 2 for Apple Watch

(Image credit: Michael Sawh)

Aura Strap 2: Performance and software

  • More reliable readings
  • Range of workouts to follow
  • Many of these features are also on normal Apple Watch.

Features score: 3/5

How the Aura Strap works has changed slightly. Previously it used a microphone to communicate measurement data via sound to the Apple Watch. Aura has ditched that approach and now uses low-energy Bluetooth to deliver readings to the Watch. It claims this approach also improves the reliability of getting a successful measurement.

It still conducts bioimpedance analysis through those electrodes, transmitting electrical current and then measures the resistance to body tissues.

After a 30-second reading, it can tell you your fat percentage, muscle, body water, visceral fat, protein, lean mass, minerals, BMI, and weight all in that one measurement. The method that you take that measurement has vastly improved not only from a process point of view but also in the reliability of taking a measurement. It’s still not faultless, but it’s noticeably more reliable.

Once you have the Aura app downloaded on your iPhone and on the Watch app, you can launch the Watch app, check the tutorial and take your first measurement. You place the electrodes on the outside of the strap on the area just below your thumb on your opposite hand, ensuring you keep your hand from touching your other hand and you keep your hands in front of your chest. During the measurement, the app will remind you of what you need to do to make sure you get a good reading.

We did experience a few bad measurements initially, but reliability does improve and it’s nice and straightforward to do. Part of the Watch screen displays small green bubbles that look like the electrodes on the outside of the case that fill as the measurement takes place and on a successful measurement, displays data in the Watch app. You’ll see a breakdown of your data along with a circular graphic that indicates whether you’re obese, jacked, twiggy or have more or less water and more or less soft tissue.

Aura says the change in the way data is now captured gives it a 95% measurement accuracy compared to clinical grade devices. To test the reliability of the Aura Strap 2’s data, we also took measurements on a set of Garmin Index smart scales at the same time. Looking into the data we found that not a lot of information matched up. Some areas like body water, BMI and overall weight were similar, but never identical based on our measurements. Data on the whole feels more reliable than previously, but it still didn’t match up to a set of smart scales.

Beyond those measurements, there’s a bit more going on in the iPhone app than before. You can track activity, heart rate and see information like calories burned, though the strap itself doesn’t track that information, that’s being pulled through from your Apple Watch tracking. 

There’s now an Aura Plus subscription service, which you need to pay up for if you want to see historical data. Without it you can only see the latest measurement recorded. With that subscription in action, you’ll see reports breaking down trends in data. There’s also recommendations based on the goals you outline when you first set up the app. 

Our measurements regularly told us were somewhat surprisingly obese despite being a relatively fit person that runs, swims and works out most days and suggested trying to do 2-3 workouts a week, reduce calories by 10-15% and add in a fat-burning workout. It did also say we had a good balance of fat and muscle, which seemed like a more reliable insight.

That leads to another new feature, which is a range of workouts you can follow, which is broken down into basic workouts, focusing on arms, chest, core and legs. There’s nothing groundbreaking here, but it does mean you can start addressing some of those insights and recommendations. Without that subscription the Aura feels very basic in terms of what you can see. While there’s a definite trend from wearables to put some features behind a subscription paywall, simple things like monthly reports feels like a feature that should be available in the free version.

Aura Strap 2 for Apple Watch

(Image credit: Michael Sawh)

Buy it if...

You want to learn more about body composition

If you don’t like stepping on a set of scales and want similar tracking from your Apple Watch, this strap will do it instead.

You want a smart strap you don’t have to charge

The Aura runs on a coin cell battery, so you don’t have to worry about carrying around a charging cable to power it.

Don't buy it if...

If you already have a smart scale and a fitness subscription

Most of the data you get on the Aura can be delivered by most connected smart scales already and they cost less to boot.

You want a smart strap that can also track your fitness

This smart strap just tracks those body composition measurements. If you’re hoping it can do more than that, you’re going to be disappointed

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Michael Sawh

Michael is a freelance journalist who has covered consumer technology for over a decade and specializes in wearable and fitness tech. Previously editor of Wareable, he also co-ran the features and reviews sections of T3, and has a long list of bylines in the world of consumer tech sites.

With a focus on fitness trackers, headphones, running wearables, phones, and tablet, he has written for numerous publications including Wired UK, GQ, Men's Fitness, BBC Science Focus, Metro and Stuff, and has appeared on the BBC Travel Show. Michael is a keen swimmer, a runner with a number of marathons under his belt, and is also the co-founder of YouTube channel The Run Testers.