Power on and off: Click Fire Button 5 times within 2 seconds to lock or unlock the mod. Variable Wattage: Turn the rotary knob at the top of the mod clockwise or counterclockwise to increase or decrease the output wattage from 5W to 30W for vaping needs. Screen display: The Screen will display the battery power, resistance of atomizer, wattage and voltage. When the atomizer is not detected, the Screen will display “Check atomizer”. When the mod is in low power, the Screen will display “Check battery”. – See more at: http://www.aspirecig.com/products/MOD/mod194.html#sthash.mNexYY0D.dpuf