An excellent vape deserves an excellent battery. Optimized to make your vapes taste better and last longer, the STYLUS is the perfect companion for your Fernway cartridge.InstructionsClick button 5x fast to turn on & offClick button 3x fast to change heat settingClick button 2x fast to preheat in cold weather or if cartridge clogs; wait for lights to cycle through, then press button & inhaleHeat settings: Low (Green, 2.6V), medium low (Blue, 3.0V), medium high (Purple, 3.4V), high (Red, 3.8V)Low means max flavor/min vapor, high means max vapor/min flavor