The 5 anatomically designed heated areas on the vest deliver consistent uniform warmth throughout the jacket. Thin, lightweight and packable, it can be easily worn as a first or second layer. Fitted with Bluetooth© technology, you can control remotely the heat settings via your smartphone, using the Thermic Heat Control App. Works with all USB powerbanks / external batteries (not included). We recommend using the Therm-ic Universal USB Powerbank to power the vest. (sold separately)