THE ALPENHEAT HEATED JACKET FIRE HAS 5 HEAT LEVELS WITH A SPECIAL HEATING CELL SYSTEM MADE OUT OF BIO-THERMAL-FIBRES WHICH ARE INCORPORATED IN THE BACKSIDE OF THE CLOTHING. THE SYNTHETIC HEATING CELLS CAN HARDLY BE FELT THROUGH THE FLEXIBLE BIO-THERMAL-FIBRES; THEREFORE IT IS VERY COMFORTABLE TO WEAR THE JACKET. FIRE INCREASES YOUR WELLBEING AT COLD TEMPERATURES; THEREFORE YOU  WANT TO MISS FIRE WHEN IN THE COLD.