Researchers from the University of California have developed a wearable designed to be worn around the arm and it actively modifies skin temperature, making the wearer feel warmer or cooler depending on their own personal preference.

See the source article by following the link below:
Researchers from the University of California have developed a wearable designed to be worn around the arm and it actively modifies skin temperature, making the wearer feel warmer or cooler depending on their own personal preference.