Free Micro USB Charging Cable Included. Charging: Plug the micro USB charging cable into the bottom of the unit. A red light indicates the battery is charging. A green light indicates that charging is completed. Turning On/Off: Click the button 5 times quickly. 3 Voltage Settings: To Change the voltage, click the button 3 times quickly. (Battery has 3 voltage settings - Low 3.4 mAh: Green | Medium 3.8 mAh: Blue | High 4.0 mAh: Red) Preheat Setting: Click the button 2 times quickly. The light will slowly change between colors and turn off when preheating is complete.