These are something truly unique... there aren't many good eGo-style batteries with both variable voltage and variable wattage. The eMax VV/VW 1300mah battery by Smoktech, like most variable eGo batteries, is adjusted with an intuitive dial at the bottom. You switch between the two settings by clicking the button 3 times - white for voltage, blue for wattage. The wattage settings range from 4w to 12w and voltage from 3.3v to 4.8v. Variable wattage on a basic eGo style battery.... awesome stuff 
