Reon Pocket, which is about the size of a Blackberry smartphone and looks like an Apple Magic Mouse, can cool your body by up to 23 degrees Fahrenheit (ca. -5 °C) on sweltering days. But it can also warm you up during the winter, maxing out at an additional 14 degrees Fahrenheit (ca. -10 °C).
To use the device, slide the boxy cooling unit into a special inner pocket on a T-shirt that sits just between your shoulder blades. Sony is selling the custom-designed shirts to accompany the Reon Pocket for about $20, but presumably, you could sew one into your own shirts to save a few bucks.
Once you’ve equipped your shirt with the cooling device just below your neck, download the free Reon Pocket app on the Google Play market or the App Store for iOS devices. From there, you can toggle between cooling and warming and adjust the temperature with one touch.
The Reon Pocket device must make contact with your skin (through your shirt) to cool you down. It uses the Peltier effect, a concept in thermodynamics, to do the actual cooling, unlike those little misting fan gizmos that you might see parents using at Disney World to cool their kids.
The Peltier effect relies on a thermocouple, or a small sensor that measures temperature through two wire legs, which are welded together on one side, forming a junction. When that junction sees a change in temperature, it creates a voltage. That, in turn, helps the thermocouple take heat measurements.
As an electric current passes through the thermocouple circuit, heat is created at one side of the junction, and absorbed at the other side. To heat or cool, the Reon Pocket just needs to take a temperature measurement through this apparatus, and either absorb heat to create a warming sensation, or release it to create a cooling effect. There’s a built-in fan for that purpose.
The built-in lithium ion battery lasts about two to four hours, depending on which settings you use, and it takes about 2.5 hours to juice the battery back up with a USB-C-style port.
While general sales began on July 1, it doesn’t look like you’re going to have much luck purchasing the wearable outside of Japan. Reon Pocket is listed on Amazon’s Japanese site for 18,500 Yen (about $172), but when I tried adding it to my basket, I was alerted that the device “cannot be delivered to the specified location” where I live in Pennsylvania.
It’s not clear when—or if—the Reon Pocket will be made available to U.S. buyers (although we assume it eventually will be). So while you wait, consider investing in a portable air conditioner.