Our Veedverks Variable Voltage Battery has three settings from 2.4 – 4.0 volts so you can customize your experience. Easy operation by tapping the end of the battery guided by easy to see color light changes so you know what setting you are using. Preheat setting warms thick oils before use. Comes with a standard 510 thread for use with all your favorite cartridges. USB Charger with rapid charge option is included.