Letter “B” means bypass, which means that the mod is under bypass mode, the voltage and wattage cannot be adjusted, and the mod will automatically adjust the output wattage or voltage according to different resistance of the coil attached.

If you want to change wattage, you need go to wattage mod, press the Fire Button and “+”button at the same time, then the screen will display the modes selection, please press the “+” or “-” button to select the mode you want, then click fire button to confirm.