The Reon Pocket does not cool a room. It cools about a palm’s worth of skin at the base of your neck and lets the rest of you draw the wrong conclusion.

Sony has been selling versions of the device since a 2019 crowdfunding launch on its First Flight platform, initially in Japan and more recently in Europe. The Reon Pocket Pro line was updated in May 2026 with the Pro Plus, a flat slab roughly the size of a thick phone that clips into a collar or a compatible undershirt and rests against the top of the spine, under your shirt, where nobody can see it.

What the hardware actually does

The mechanism is the Peltier effect, which is neither new nor exotic. Push a current across the junction of two dissimilar semiconductors and heat moves from one side to the other. One face gets cold, the other gets hot, and no heat leaves the system.

Sony’s engineering problem has never really been making the cold side cold. Shedding heat off the other side fast enough that the device does not defeat itself is the harder half, and nearly every generation has spent its upgrades on fans, vents and dissipation, not on the thermoelectric module. The Pro Plus exhausts through a narrow grille designed to clear a high collar. Sony says the new model improves cooling performance by two degrees Celsius over its predecessor and that redesigned fins hold it 40 per cent more stably on the neck and shoulders; those are launch figures from the company’s own testing, and nobody outside Sony has verified them.

Why the neck is the chosen patch

Sony’s stated reason for the placement is blood flow close to the surface. The physiology literature makes a related but sharper point, and it does not flatter the neck quite as much as that explanation suggests. The body region with the clearest outsized say in whole-body comfort is the face, not the neck.

The most-cited work here is a 2005 paper by James Cotter and Nigel Taylor in the Journal of Physiology, which clamped core and skin temperatures in thirteen men, then warmed or cooled ten separate skin sites to see which ones moved whole-body thermal discomfort the most. Facial stimulation came out on top, well ahead of the other sites tested, with the limb extremities ranking lowest. A Waseda University group led by Mayumi Nakamura reached a similar conclusion in the Journal of Applied Physiology in 2008: cooling the face was the most comfortable local stimulus under mild heat, more so than the chest, abdomen or thigh. Neck-specific evidence is thinner. When Nakamura’s team extended the same method to the neck in a 2012 paper in the European Journal of Applied Physiology, the neck behaved differently from the abdomen under local cooling, though nothing in that result put the neck on a par with the face.

If the face is where the physiology is strongest, why does every consumer device end up on the neck? The practical answer has little to do with thermosensitivity. Nobody is going to wear a cooling plate on their cheek to the office, and the neck is the compromise: sensitive enough to register, discreet enough to sell.

These are also small studies. Sample sizes in the low teens, largely male, run in climate chambers with water-perfused pads rather than consumer hardware on a crowded train. None of them tested a Peltier wearable directly. The leap from laboratory site-mapping to a specific product is the reader’s to make, not a conclusion the researchers reached themselves.

What the sensation does not buy you

Feeling cool and being cool are separate states, and the device only reliably delivers one of them.

A 2025 chamber study led by Jue Wang, published in Case Studies in Thermal Engineering, tested head and neck cooling on workers in a simulated high-temperature mine and found that cooling those regions produced no significant change in core temperature while substantially improving how the twenty-four participants rated their comfort. Cotter and Taylor raised a sharper version of the same point two decades earlier: the face is also highly sensitive for sweating control, so cooling it can suppress general sweat output and, under real heat stress, potentially increase heat storage instead of reducing it.

Sony makes no claim about heat illness, and that caveat belongs to a clamped laboratory setup and to facial cooling specifically, not to a neck-worn consumer product. What goes missing in the shorthand is the distinction itself. Calling the thing a wearable air conditioner implies it does what an air conditioner does.

The building-energy case underneath the gadget

The more consequential application of this effect has nothing to do with personal comfort.

A 2021 study led by Bin Yang, published in Energies, tested two wearable face and neck cooling fans in warm indoor conditions and cut local skin temperatures by up to 2.1 degrees Celsius. Thermal sensation votes moved enough that participants accepted an air-conditioning setpoint of 32 degrees Celsius. Against a 24.5 degree baseline, the authors calculated that as a 45.7 per cent energy saving.

Those were fans, not Peltier modules, and one small controlled study is not a retrofit programme. Scale changes the arithmetic. A few watts aimed at 5.5 per cent of a person’s skin, buying several degrees of tolerance on a chiller that serves an entire floor, stops being a novelty purchase; it becomes a line item in a facilities budget.

What to watch

Sony has not confirmed a United States release for the Pro Plus, and the product has spent most of its life as a Japan-first item with intermittent Western availability. Wider availability for individual buyers is the nearer-term question. Whether any employer eventually treats the same physiology as a facilities decision, handing devices out instead of running the air conditioning harder, is the slower-moving one.