The Ego Twist battery does exactly what the name suggests, it twists at the bottom. The reason why it twists is to vary between different voltage strengths. The eGo Twist 1,300mAh replacement or upgrade batteries are a great product that makes any standard cartomizer or clearomizer work to their full potential. Adjustable from 3.2 volts to 4.8 volts with a TWIST of the end cap on the bottom of the battery, this is a fast and simple way to dial in just the right taste or vapor you feel like in a second. They possess the eGo-C 5 clicks on/off feature, simply click the button 5 times fast to arm on or 5 times again for off. The LED on the button will flash to show its changed state. The twist is a bit longer than a standard ego due to the internal workings that let the user change the voltage with a simple twist. With all the different e-cigarette products that come out every month, this is still my day and night choice when it comes to batteries and getting the best results for flavor and power. The top end of 4.8 volts is enough as its stats to burn the flavor out of the juice. Our customers' rate this product as a close ten out of ten for ease of use and as the best allrounder that should be in everyone's vaping kit.