Is the Sony Reon Pocket 5 the perfect device for beating the heatwave?

When I went hands-on with the Sony Reon Pocket 5 back in April, I was full of optimism for a long, hot summer during which I could put it to the test.

That summer is yet to materialise, but the turbulent British weather has at least given me the opportunity to make use of both the heating and cooling abilities of Sony’s new “wearable thermo device”.

Having spent time with it around my neck on multiple Tube journeys, at a sunny summer social and during a few chilly evening walks, my feelings about it are mixed. It’s innovative and capable of providing some light relief when it’s particularly hot or cold, but it isn’t as effective as I had hoped. 

Sony Reon Pocket 5 review: What do you get for the money?

The Sony Reon Pocket 5 was initially only available to purchase directly from Sony but has recently been listed on Amazon and will set you back £139. Included in the box are the heating/cooling device, the neckband it clips into, short and long air vent covers, a USB-A to USB-C charging cable and the Reon Pocket Tag, which houses sensors that measure environmental conditions around you.

The included neckband is suitable for neck sizes ranging from 34cm to 46cm but Sony also sells a smaller version designed for those with necks of a circumference between 29cm and 35cm. This will cost you an additional £25 and is a different colour – “Cream” as opposed to the standard white neckband.

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Sony Reon Pocket 5 review: How does it work?

The Reon Pocket 5 is worn around your neck (underneath your clothes), with the main unit resting just below your nape, between the shoulder blades. Contained within this unit is a battery-powered Peltier element (commonly used in camping fridges) that heats up or cools down when you engage the Warm or Cool modes via the Reon Pocket mobile app.

Warm mode has four levels, while Cool mode has five, and battery life is dictated by which is in use. With the lowest level of cooling (Level 1), battery life is quoted at around 17 hours. That figure falls to 12 hours at Level 2, 10 hours at Level 3, 7.5 hours at Level 4 and just 4 hours at the coolest Level 5 setting. The warming functionality is more battery-intensive, with the Reon Pocket 5 lasting around 8 hours at Level 1, 6 hours at Level 2, 5 hours at Level 3 and 4 hours at Level 4.

Both the Warm and Cool modes have smart setting options that automatically adjust their level based on temperature and humidity readings taken by sensors built into the device. The Reon Pocket 5 also has an in-built fan that can run at three different speeds and has a dedicated section in the app.

To experience fully what the Reon Pocket 5 has to offer, however, you’ll want to link it with the Reon Pocket Tag and clip the tag onto your clothes. The Tag has light, proximity and acceleration sensors in addition to sensors for temperature and humidity and unlocks Smart Cool ⇔ Warm mode. When engaged, this mode picks up on changes in your environmental conditions and adapts the Pocket 5’s temperature settings in real-time. This mode does impact the battery life figures stated above quite considerably, though.

Sony Reon Pocket 5 review: Is it effective?

Having used the Reon Pocket 5 for several weeks, I’m still on the fence about its effectiveness. On the one hand, there’s no disputing the fact its Peltier element heats up and cools down to a notable degree.

Engaging the highest level of cooling and letting it do its thing for a few minutes produced an effect akin to holding an ice pack against my skin, although it wasn’t quite as frosty. Switching over to the strongest Warm mode setting provided a similar feeling to what I’ve experienced when applying heat patches to football-related aches and pains.

The trouble is, the healing and cooling effects are relatively localised as the conductive section that makes contact with your skin is only 5cm tall by 4.5cm wide. In theory, the effect should spread down your body over time but my experience didn’t always tally with this. While I was very much aware of a change in temperature near the Reon Pocket 5, I was conscious that other areas of my body were still feeling rather toasty or nippy. The heating effect worked slightly better in this regard, with some warmth spreading to my shoulders.

This is illustrated clearly in the pictures below, which were taken using the Flir One Pro thermal camera. The first image shows my body temperature in its natural state and then after wearing the Reon Pocket 5 for ten minutes with the Cool setting at maximum. The darker colours around the device indicate that the temperature there has dropped:

The second image shows my natural body state versus the result of wearing the Reon Pocket 5 for ten minutes with the Warm setting at its maximum level. Here, the brighter area where the device had been shows that it’s warmer than before the device was put on and some of this heat has made its way across my shoulder blades:

Despite only being truly impactful on a local level, I was grateful for the light relief it provided at both ends of the temperature spectrum. On the hottest day of the year, I was pleased to have the Reon Pocket 5 on hand to make a sweaty Northern Line Tube journey and trek to a product launch just that little bit more bearable. When temperatures fell and I started to feel a little chilly, the warmth at the base of my neck was comforting. That’s probably about all you can ask of a device as small and relatively inexpensive as this.

My experience with the automatic Smart Cool/Warm mode was positive but only once I’d made use of the in-app personalisation options. With the default settings engaged, I often found that the changes made based on the Pocket Tag’s measurements didn’t correspond with what I wanted. There were several times when the Reon Pocket 5 decided that I was cool enough and started to warm up again despite me still feeling rather hot and wanting the highest level of cooling to continue.

Fortunately, this is remedied easily enough by setting the temperatures at which the Reon Pocket 5 switches modes and how aggressively it seeks to cool or warm you at those temperatures. After a bit of trial and error, I managed to get things set up in such a way that I felt comfortable with the changes the device was making. The app itself takes a bit of working out but once I was familiar with it, it was a painless enough experience.

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Sony Reon Pocket 5 review: What could be improved?

The easy thing to say here would be for Sony to increase the surface area of the Reon Pocket 5’s heating and cooling element. Doing so would enable it to affect a more sizeable section of your back and have a greater impact on body temperature. But it would also make the device a lot less practical to wear and I didn’t find it all that comfortable as it is.

It’s not especially heavy at 164g with the large vent attached, but I found it impossible to forget that I had it on and often caught myself craning my neck forward slightly because of its presence. I found the arms holding it in position dug into the front of my neck a bit, too, so I needed to take the device off for some respite every once in a while.

Given this is the fifth iteration of the product (the first four were only available in Asia), I’m sure the Japanese manufacturer has agonised over trying to balance effectiveness and comfort. Ultimately, having a chunk of plastic around your neck isn’t anyone’s idea of fun but future generations of the Reon Pocket would benefit from being more agreeable to wear.

I have a couple of other issues with the design. For optimal results, you’ll want to be wearing a collared shirt. This helps retain heat better than loose-fitting clothing when using Warm mode and allows the vent to direct hot air out more effectively in Cool mode. Given I live in Polo shirts all year round, this isn’t a problem for me, but I can’t help thinking this will put off a pretty significant group of consumers.

Its appearance will also prove polarising. It isn’t all that obvious to others that you’re wearing it – the only sign is the slim vent poking out at the top of your collar – but I felt quite conspicuous nonetheless and got several odd looks while wearing it on the Tube. The mere design of the thing was enough to dissuade a female friend from trying it on; she described it as looking like the kind of apparatus used by a gynaecologist.

My other word of warning is that the fan can get rather loud when working flat out. It’s not going to disturb others on a bustling train and is no more egregious than a portable fan, but it might prove distracting in quieter environments.

Sony Reon Pocket 5 review: Should you buy it?

The Sony Reon Pocket 5 is one of the trickiest products to evaluate and provide buying advice on that I’ve tested for Expert Reviews. Not because it’s fatally flawed or doesn’t work as intended – if that were the case I could dismiss it outright – but because the issue it sets out to tackle is such a personal one.

Did I find it of benefit when volatile London temperatures skyrocketed and plummeted within the same week? Yes. But whether you’d experience the same level of relief I did is impossible to say and, while reasonably affordable, you could just buy a cheaper battery-powered portable fan, or pack a nice warm jumper instead.