Dial into your voltage with the silky smooth twist knob at the bottom of the battery that allows you to adjust between 2.0 Volts and 4.0 Volts. Includes: - HoneyStick Twist Vape Pen Battery - 500mAh / Variable Voltage / Preheat function - 0.5ml Capacity Vape Cartridge (refillable with ceramic heater) - USB Charger