With the Oakland Oil Vape pen there are 3 variable voltage levels.Use the lowest voltage for the best flavor. Use a higher voltage for colder environments. By tapping the bottom of the battery 4 times you can perform a preheat function. Preheat function can last 28 seconds and can be stopped by tapping the bottom of the battery once. Voltage can be adjusted by tapping the bottom of the battery 3 times and can be determined by the color of the battery light.