Vision eGo Spinner 1300mAh Variable Volt Battery $24.50

It is the largest variable volt eGo battery with 510/eGo threading, so it works with a variety of 510/eGo atomizers or tanks, or clearomizers.

The battery allows you to adjust voltage output from 3.3v to 4.8v by spinning the knob at the bottom. Each increment is 0.5v.