It is button activated, 5 clicks to turn on/off the device.
With preheat feature, C04 works good for both thin and very thick oil. No matter CBD, or THC/ THCO oil, it can perform well. When using thick oil, just press the button 2 times to warm up , you will get smoother hit.
If you like bigger clouds, just press the button 3 times to change the voltage between 2.4V to 3.2V. There is always one voltage setting that meets your requirement.