REON POCKET warms and cools the back of the neck

A chilly street can give way to a warm subway carriage, leaving the back of the neck hot while both hands are too full to take off a coat. Sony's REON POCKET addresses such changes with a small metal plate against the skin. A neckband holds the device against the upper back, where the contact surface can cool or warm.

REON POCKET PRO Plus, launched in Japan in April 2026, follows the same principle. Its reach differs from an air conditioner that changes the air in a room: it exchanges heat at the skin surface beneath a stainless-steel plate. Unlike a handheld fan or heat pack, one device can switch between cooling and warming.

Inside is a semiconductor component called a Peltier element. An electric current makes one side absorb heat while the other becomes hot. During cooling, the cold side faces the skin, and a heat sink and fan release the transferred heat into the air. Reversing the current reverses the heat flow, allowing the same plate to provide warmth. Even cooling a small plate requires somewhere for the heat on the opposite side to go.

PRO Plus has two independent thermal modules that alternate their cooling intensity. Because the device sits beneath clothing, its air outlet matters too. The exhaust attachment can be adjusted in length and angle to keep hot air from being trapped inside a shirt. Cooling depends both on keeping the plate steadily against the skin and on giving the outgoing air a clear path.

Connecting the separate REON POCKET TAG enables a mode that switches automatically between cooling and warming using ambient temperature and humidity readings. This reduces the need to change settings when moving between outdoor air and heated rooms. Manual controls remain available for both functions; automatic switching requires the tag.

Changing the temperature of a plate against the neck is not the same as lowering the temperature of the whole body. The device adjusts the sensation of warmth or coolness at the contact area. Even within that small area, the heat-absorbing semiconductor, the neckband, and the exhaust path must work together. A device hidden beneath a shirt needs to manage both where heat enters and where it leaves.